Update Animation Documentation

[BMaxV]

After figuring out some details on the animation system with help from entikan, there was a question in the help channel that the documentation should imo answer:

How to get a blender animation into panda.

• export via yabee
• convert blend2bam
• use gltf export and panda3d-gltf

Concerning the turn around time for pull requests, I would suggest we agree on a few hours sometime, write it down and get it merged right away. I'm not in the mood to write a good-ish update and have it sit in PRs for months.