htmlq: add page (#15625)

Co-authored-by: Wiktor Perskawiec <git@spageektti.cc>
Co-authored-by: Juri Dispan <juri.dispan@posteo.net>
Co-authored-by: Managor <42655600+Managor@users.noreply.github.com>

pages/common/htmlq.md

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+# htmlq
+
+> Use CSS selectors to extract content from HTML files.
+> More information: <https://github.com/mgdm/htmlq>.
+
+- Return all elements of class `card`:
+
+`cat {{path/to/file.html}} | htmlq '.card'`
+
+- Get the text content of the first paragraph:
+
+`cat {{path/to/file.html}} | htmlq --text 'p:first-of-type'`
+
+- Find all the links in a page:
+
+`cat {{path/to/file.html}} | htmlq --attribute href 'a'`
+
+- Remove all images and SVGs from a page:
+
+`cat {{path/to/file.html}} | htmlq --remove-nodes 'img' --remove-nodes 'svg'`
+
+- Pretty print and write the output to a file:
+
+`htmlq --pretty --filename {{path/to/input.html}} --output {{path/to/output.html}}`