gh-106318: Add string method examples

[blaisep]

This PR reformats the examples created by @adorilson in #105670
I followed the discussion in a related PR #111743 , and then discussed it with @encukou and @CAM-Gerlach .
We decided that the fastest way to get the content into the docs was to edit the stdtypes.rst to include various suggestions and to have me update the related PR
So I pulled the branch, resolved merge conflicts, edited the file and created this PR.

Mentioning others who might be interested:
@hauntsaninja , @CAM-Gerlach , @encukou

• Issue: Add examples to docs for str methods #106318

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📚 Documentation preview 📚: https://cpython-previews--119445.org.readthedocs.build/en/119445/library/stdtypes.html

[hugovk]

This change needs reverting.

[hugovk]

I think this might fix the Sphinx error:

Suggested change

	The original string is returned if *width* is less than or equal to ``len(s)``.
	The original string is returned if *width* is less than or equal to ``len(s)``.

For some reason, reST is usually indented in multiples of 3 spaces.

[blaisep]

I'll update this with the suggestions from https://www.youtube.com/live/-0SXSTkJsfg?si=yRQG9Pm0ochACy_x&t=3883

[adorilson]

I notice some possible errors, @blaisep

[blaisep]

I notice some possible errors, @blaisep

Yes, I am marking this draft and going over it much more carefully. BTW, @adorilson , I will be in UTC-4 for the rest of the week and happy to pair up on this if you like. I'll add you to my fork.

[adorilson]

This is supposed to be:

'Guido was born in Netherlands'

However, I think the previous example is more valuable. It shows the two Default class behaviour.

[adorilson]

It could be closed in favor of all other PR linked to #106318