The dunder methods __aenter__ and __aexit__ that are implemented in several classes in tg.(ext) (Updater, Application, Bot, BaseRequest, BaseUpdateProcessor) should get docstrings that explain how these methods behave.

• Since the behavior is very similar in most cases, usage of sphinx insertions may be beneficial
• The notes that we currently have in the class docstring regarding context manager behavior can possibly be (party) replaced by references to these methods
• Sphinx needs to be configured to show these docstrings