This PR:
* Splits the `Gotchas` page into several sub-sections. This was getting too big and hard to navigate.
* Adds some information regarding Python instances life-time of objects wrapping Blender internal data.
* Adds some information about usage of constructors and destructors for sub-classes of Blender-defined types.
Pull Request: https://projects.blender.org/blender/blender/pulls/129814
