add example for too-many-format-args and too-few-format-args message documentation

[gunungpw]

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Type of Changes

	Type
✓	📜 Docs

Description

• add code example for too-many-format-args
• add code example for too-few-format-args
• add official Python docs for string formatting in related.rst

Ref #5953

[Pierre-Sassoulas]

Nice and clear !