Found the following HTML validation problems:
adjust_luminance.html:110:1: Warning: <img> lacks "alt" attribute
cell_borders.html:90:1: Warning: <img> lacks "alt" attribute
cell_borders.html:124:1: Warning: <img> lacks "alt" attribute
cell_fill.html:88:1: Warning: <img> lacks "alt" attribute
cell_text.html:163:1: Warning: <img> lacks "alt" attribute
cells_body.html:148:1: Warning: <img> lacks "alt" attribute
cells_column_labels.html:150:1: Warning: <img> lacks "alt" attribute
cells_column_spanners.html:145:1: Warning: <img> lacks "alt" attribute
cells_footnotes.html:150:1: Warning: <img> lacks "alt" attribute
cells_grand_summary.html:160:1: Warning: <img> lacks "alt" attribute
cells_row_groups.html:152:1: Warning: <img> lacks "alt" attribute
cells_source_notes.html:135:1: Warning: <img> lacks "alt" attribute
cells_stub.html:148:1: Warning: <img> lacks "alt" attribute
cells_stub_grand_summary.html:151:1: Warning: <img> lacks "alt" attribute
cells_stub_summary.html:169:1: Warning: <img> lacks "alt" attribute
cells_stubhead.html:131:1: Warning: <img> lacks "alt" attribute
cells_summary.html:183:1: Warning: <img> lacks "alt" attribute
cells_title.html:142:1: Warning: <img> lacks "alt" attribute
cols_align.html:97:1: Warning: <img> lacks "alt" attribute
cols_hide.html:85:1: Warning: <img> lacks "alt" attribute
cols_hide.html:106:1: Warning: <img> lacks "alt" attribute
cols_label.html:98:1: Warning: <img> lacks "alt" attribute
cols_label.html:117:1: Warning: <img> lacks "alt" attribute
cols_merge.html:117:1: Warning: <img> lacks "alt" attribute
cols_merge_n_pct.html:152:1: Warning: <img> lacks "alt" attribute
cols_merge_range.html:128:1: Warning: <img> lacks "alt" attribute
cols_merge_uncert.html:141:1: Warning: <img> lacks "alt" attribute
cols_move.html:93:1: Warning: <img> lacks "alt" attribute
cols_move_to_end.html:83:1: Warning: <img> lacks "alt" attribute
cols_move_to_end.html:96:1: Warning: <img> lacks "alt" attribute
cols_move_to_start.html:84:1: Warning: <img> lacks "alt" attribute
cols_move_to_start.html:97:1: Warning: <img> lacks "alt" attribute
cols_unhide.html:84:1: Warning: <img> lacks "alt" attribute
cols_unhide.html:93:1: Warning: <img> lacks "alt" attribute
cols_width.html:108:1: Warning: <img> lacks "alt" attribute
currency.html:92:1: Warning: <img> lacks "alt" attribute
data_color.html:162:1: Warning: <img> lacks "alt" attribute
data_color.html:195:1: Warning: <img> lacks "alt" attribute
default_fonts.html:67:1: Warning: <img> lacks "alt" attribute
extract_summary.html:125:1: Warning: <img> lacks "alt" attribute
fmt.html:121:1: Warning: <img> lacks "alt" attribute
fmt_bytes.html:208:1: Warning: <img> lacks "alt" attribute
fmt_bytes.html:222:1: Warning: <img> lacks "alt" attribute
fmt_currency.html:293:1: Warning: <img> lacks "alt" attribute
fmt_currency.html:311:1: Warning: <img> lacks "alt" attribute
fmt_date.html:161:1: Warning: <img> lacks "alt" attribute
fmt_date.html:183:1: Warning: <img> lacks "alt" attribute
fmt_datetime.html:345:1: Warning: <img> lacks "alt" attribute
fmt_engineering.html:174:1: Warning: <img> lacks "alt" attribute
fmt_fraction.html:243:1: Warning: <img> lacks "alt" attribute
fmt_integer.html:205:1: Warning: <img> lacks "alt" attribute
fmt_markdown.html:125:1: Warning: <img> lacks "alt" attribute
fmt_number.html:249:1: Warning: <img> lacks "alt" attribute
fmt_number.html:268:1: Warning: <img> lacks "alt" attribute
fmt_partsper.html:262:1: Warning: <img> lacks "alt" attribute
fmt_passthrough.html:119:1: Warning: <img> lacks "alt" attribute
fmt_percent.html:236:1: Warning: <img> lacks "alt" attribute
fmt_scientific.html:180:1: Warning: <img> lacks "alt" attribute
fmt_time.html:134:1: Warning: <img> lacks "alt" attribute
fmt_time.html:156:1: Warning: <img> lacks "alt" attribute
ggplot_image.html:120:1: Warning: <img> lacks "alt" attribute
google_font.html:75:1: Warning: <img> lacks "alt" attribute
google_font.html:102:1: Warning: <img> lacks "alt" attribute
grand_summary_rows.html:130:1: Warning: <img> lacks "alt" attribute
gt.html:146:1: Warning: <img> lacks "alt" attribute
gt.html:164:1: Warning: <img> lacks "alt" attribute
gt_preview.html:91:1: Warning: <img> lacks "alt" attribute
html.html:66:1: Warning: <img> lacks "alt" attribute
info_currencies.html:83:1: Warning: <img> lacks "alt" attribute
info_currencies.html:91:1: Warning: <img> lacks "alt" attribute
info_date_style.html:51:1: Warning: <img> lacks "alt" attribute
info_google_fonts.html:55:1: Warning: <img> lacks "alt" attribute
info_locales.html:75:1: Warning: <img> lacks "alt" attribute
info_paletteer.html:151:1: Warning: <img> lacks "alt" attribute
info_time_style.html:51:1: Warning: <img> lacks "alt" attribute
local_image.html:100:1: Warning: <img> lacks "alt" attribute
md.html:65:1: Warning: <img> lacks "alt" attribute
opt_align_table_header.html:90:1: Warning: <img> lacks "alt" attribute
opt_all_caps.html:102:1: Warning: <img> lacks "alt" attribute
opt_css.html:102:1: Warning: <img> lacks "alt" attribute
opt_footnote_marks.html:140:1: Warning: <img> lacks "alt" attribute
opt_horizontal_padding.html:116:1: Warning: <img> lacks "alt" attribute
opt_row_striping.html:89:1: Warning: <img> lacks "alt" attribute
opt_table_font.html:111:1: Warning: <img> lacks "alt" attribute
opt_table_font.html:134:1: Warning: <img> lacks "alt" attribute
opt_table_lines.html:91:1: Warning: <img> lacks "alt" attribute
opt_table_outline.html:94:1: Warning: <img> lacks "alt" attribute
opt_table_outline.html:101:1: Warning: <img> lacks "alt" attribute
opt_vertical_padding.html:116:1: Warning: <img> lacks "alt" attribute
pct.html:71:1: Warning: <img> lacks "alt" attribute
px.html:68:1: Warning: <img> lacks "alt" attribute
row_group_order.html:77:1: Warning: <img> lacks "alt" attribute
sub_large_vals.html:135:1: Warning: <img> lacks "alt" attribute
sub_large_vals.html:149:1: Warning: <img> lacks "alt" attribute
sub_large_vals.html:165:1: Warning: <img> lacks "alt" attribute
sub_missing.html:108:1: Warning: <img> lacks "alt" attribute
sub_small_vals.html:135:1: Warning: <img> lacks "alt" attribute
sub_small_vals.html:148:1: Warning: <img> lacks "alt" attribute
sub_small_vals.html:164:1: Warning: <img> lacks "alt" attribute
sub_zero.html:115:1: Warning: <img> lacks "alt" attribute
summary_rows.html:140:1: Warning: <img> lacks "alt" attribute
tab_footnote.html:146:1: Warning: <img> lacks "alt" attribute
tab_header.html:80:1: Warning: <img> lacks "alt" attribute
tab_options.html:590:1: Warning: <img> lacks "alt" attribute
tab_options.html:598:1: Warning: <img> lacks "alt" attribute
tab_options.html:605:1: Warning: <img> lacks "alt" attribute
tab_options.html:617:1: Warning: <img> lacks "alt" attribute
tab_options.html:627:1: Warning: <img> lacks "alt" attribute
tab_options.html:638:1: Warning: <img> lacks "alt" attribute
tab_row_group.html:108:1: Warning: <img> lacks "alt" attribute
tab_row_group.html:129:1: Warning: <img> lacks "alt" attribute
tab_source_note.html:71:1: Warning: <img> lacks "alt" attribute
tab_spanner.html:128:1: Warning: <img> lacks "alt" attribute
tab_spanner_delim.html:106:1: Warning: <img> lacks "alt" attribute
tab_stubhead.html:73:1: Warning: <img> lacks "alt" attribute
tab_style.html:135:1: Warning: <img> lacks "alt" attribute
tab_style.html:160:1: Warning: <img> lacks "alt" attribute
tab_style.html:179:1: Warning: <img> lacks "alt" attribute
text_transform.html:87:1: Warning: <img> lacks "alt" attribute
web_image.html:102:1: Warning: <img> lacks "alt" attribute
web_image.html:136:1: Warning: <img> lacks "alt" attribute