Broken links related to COC

[orbeckst]

• linkbto coc in https://www.mdanalysis.org/pages/community/ is broken
• Unformatted markdown link to GitHub in coc blog post
• ?? No direct link to coc in sidebar — maybe we decided to not have that anymore in restructuring but wanted to mention. Had to find it through Community

[orbeckst]

The PR does not add a link to the sidebar.

There are also MANY broken links to the old location /pages/conduct. Not sure how to handle them — I can just fix all of them. I don't know how to do a redirect without doing this on Cloudflare (where we only have a small number of free redirects IIRC).

[orbeckst]

Changing all links

git grep -l '/pages/conduct' | xargs perl -wpi~ -e 's(/pages/conduct/)(/conduct)'