Documenting issues with website and documentation repos

Right now there are some problems or annoyances that we cannot solve with the current setup of documentation and website in different repos.

Let me add this list here for reference, maybe in the future we can solve this:

• cross linking between them must use external urls, otherwise references won't be found.
• we cannot mount documentation "inside" the website (using hugo mounts), because it will use only one theme, and we have a separated theme for the docs.
• we cannot use aliases in the documentation (e.g. /installation was used a lot in blog posts) to use both urls properly.
• updating the documentation triggers a deployment of the website, but the changes from the documentation will not be picked up due to the submodule reference. A separate PR to the website is currently necessary (should be fixed by #115)

The issue names the separate website and documentation repositories but no files or tests. Start by reviewing the Hugo mounts and aliases references, the cross-linking concerns, and issue #115. Done would require an agreed resolution for the listed cross-repository problems.