Document guarantees provided when sharing built-in types across threads

[lysnikolaou]

Documentation

The documentation lacks proper notes for guarantees around sharing built-in types across threads. I'm planning to start opening PRs to improve on that.

Linked PRs

• gh-142518: Document thread-safety guarantees of list operations #142519
• [3.14] gh-142518: Document thread-safety guarantees of list operations (GH-142519) #143736
• gh-142518: Document thread-safety guarantees of dict operations #144184
• gh-142518: Define lock-free and per-object lock #144548