Add troubleshooting section for building

[Newbytee]

This is currently very short and brief. I would add more things, but I can't think of anything else right now. Suggestions welcome.

[bbhtt]

Are there any plans to continue this? It'd be better to mention the shallow cloning thing here https://docs.flatpak.org/en/latest/module-sources.html#git-sources

[Newbytee]

Are there any plans to continue this? It'd be better to mention the shallow cloning thing here https://docs.flatpak.org/en/latest/module-sources.html#git-sources

Yes, I'd like to see this merged. The question is just what needs to be here for it to be merged.

It'd be better to mention the shallow cloning thing here https://docs.flatpak.org/en/latest/module-sources.html#git-sources

It's already mentioned there, sort of (the error message isn't mentioned). And regardless, my idea for this page would be to have a list of common errors that people easily can refer to if they have problems without having to dig through the docs.

[bbhtt]

The question is just what needs to be here for it to be merged.

The page is too small to be merged right now.