* Added a TL;DR first paragraph summarizing that one shall not keep any
reference to Blender data when modifying its container.
* Added some info about fact that adding items to some data containers
(like Collection) can also invalidate existing items (due to array
re-allocation).
* Added a Do/Don't example which shows a crash after adding some items
to a collection.
Related to T61297.
49c100e56c