Add an 'unsupported on android' warning to 2d skeleton documentation

[kjav]

No description provided.

[Calinou]

I'd make the disclaimer more precise and mention HTML5 as well. 2D skeletons should work on Android when using the GLES3 renderer. See godotengine/godot#41927.

[kjav]

Hi @Calinou - good point, I'll add in something about HTML5. However the GLES3 renderer is also broken in a different way; the issue here explains that there can be colour problems with it godotengine/godot#35772 (comment)

[Calinou]

You can amend your pull request instead of opening a new one 🙂

[kjav]

@Calinou Thanks - I was going to close this one as it seems you covered it in that other issue you opened (godotengine/godot#41927) - unless that one is just in the editor and not in the docs?

[Calinou]

@kjav That PR is only for the class reference, not the documentation page.

[kjav]

Thanks Calinou, I didn't realise that. I'll update the message

[NathanLovato]

I took the liberty to edit the message directly to save you some time.

[NathanLovato]

Thanks for your contribution!