Outdated / unclear links in the new Confluence wiki

[pitkant]

Describe the bug
Due to project documentation having been moved to Confluence wiki, it is now unclear where issues and pull requests related to Helsinki API documentation should be opened. For example Dokumentaatiokäytännöt website links to this bestpractice repository. Koodikontribuutioiden hyväksyminen links to nowhere.

Additional points:

• Some documentation that used to live in dev.hel.fi website no longer exists.
• Confluence wiki seems to be less accessible to outsiders as some documentation is hidden from the public.

Desktop (please complete the following information):

• OS: macOS 13.0.1
• Browser Safari
• Version 16.1