Broken link in contribute section
Originally created by @BitingBird on #8847 (Redmine)
https://tails.boum.org/contribute/how/documentation/ links to https://labs.riseup.net/code/projects/tails/issues?query_id=118 which was removed. The new link is https://labs.riseup.net/code/projects/tails/issues?query_id=172 for end-user doc, and https://labs.riseup.net/code/projects/tails/issues?query_id=173 for contributors doc. The page should probably link to both, and the second one be added to https://tails.boum.org/contribute/how/code/ (which should mention that documenting new features is not optionnal, btw).