fix(docs): fix animation for menu-toggle

[devversion]

Little explanation:

• When opening demo through link (example: http://127.0.0.1:8080/#/demo/bottomSheet), we need to wait for the ul being rendered. (using the next tick)
• So I register the complete watcher in the next tick without affecting the current code.
• The current problem for the open animation is, that we read the height in the timeout, so we need to move that out -> but then it won't wait for the ul to be rendered on opening through link. So as I did, we need to delay the watcher registration - and everything works.

Refrences #6579 References #6572 Fixes #6262 Fixes #6936