proposal: remove obsidian theme plugin temporarily

[EsenDR]

Are you certain it's a bug?

• [x] Yes, it looks like a bug

Are you sure this is not an issue in Docusaurus?

• [x] It is not a Docusaurus issue

Is there an existing issue for this?

• [x] I have searched existing issues, it hasn't been reported yet

Issue description

With the theme not being updated in the last month, I propose we move back to default theme of Starlight. We can always re-update to bring back the theme once it has been fixed. I think it would be better to have an updated and non-borked setup than to continue with an outdated release of the website.

Another thing to change are the issue templates on GitHub as the bug report still includes the former docs generator Docusaurus.

EDIT: It might be a good idea to also add an "Other" template for issues as technically this doesn't fit in as a bug nor anything else listed.