Robert

@Calinou This is my draft for the changes discussed in #6793. Let me know if I should change anything. The instancing demo hasn't been updated yet so I think it...

Added a note about how to download the demo directly from github:

As suggested by @YuriSizov in #5121 I removed the `:article_outdated: True` Tag with the latest update to this PR.

@Calinou I added a note about the download-service which could be removed later on.

@wirecat The original idea was to link to the [asset store](https://godotengine.org/asset-library/asset/148) which in turn references the release tag you mentioned: I added the note in the PR to allow a...