Update TileSets and TileMaps documentation for Godot 4.0

[Calinou]

The documentation was split into two pages, as there are much more features to cover now.

There are still features to document, but this should be a good start to review and proofread already. I've tried to keep the documentation concise but also detailed enough to cover complex use cases, while also being accessible to beginners.

TODO

• Document terrains.
  • Documentation quality may be subpar on this aspect, as I've had trouble understanding how the terrain system works.
• Document tile proxies.
• Document scene tile import.

[skyace65]

Didn't get to do a read through, just checked it for spelling and grammar errors. These two were the only I found.

[letmetrythisname]

Great work overall. Just made a few revisions to both documents: mainly corrected uses of passive voice and truncated/split longer sentences to make them easier to read.
isaac-edits-diff.txt

[Calinou]

Great work overall. Just made a few revisions to both documents: mainly corrected uses of passive voice and truncated/split longer sentences to make them easier to read. isaac-edits-diff.txt

Thanks! I've applied those changes and added you as a co-author 🙂

[mhilbrunner]

Pushed to make CI happy (adding a newline at the end of the index file, fixing a readadd -> re-add typo and erroneous space at a beginning of a line in using_tilemapst.rst).

Great work, thanks!