gh-123407: Allow translation of doctest blocks content

[m-aciek]

Refs #123407. Doctest blocks are the second type of blocks present in Python documentation, that need a separate configuration value. Example:

cpython/Doc/tutorial/introduction.rst

Lines 150 to 155 in e094420

	>>> 'spam eggs' # single quotes
	'spam eggs'
	>>> "Paris rabbit got your back :)! Yay!" # double quotes
	'Paris rabbit got your back :)! Yay!'
	>>> '1975' # digits and numerals enclosed in quotes are also strings
	'1975'

Disclaimer: changing the Sphinx config doesn't seem to make expected difference.

• Issue: Docs: enable translations of code blocks #123407

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