[Docs] Add more examples to MANIFEST.in explanation

[jeanas]

Summary

I'm migrating pypa/packaging.python.org#989 since the relevant document has moved here with #4108.

Posted by @shi-yan:

"""
this is a poor document regarding manifest.in usage.

https://packaging.python.org/guides/using-manifest-in/

for example it doesn't contain any example for using recursive-include

recursive-include folder
recursive-include parent/folder

don't work at all.

it has to be

recursive-include folder *.html

"""

OS / Environment

No response

Additional Information

Examples should be added.

Code of Conduct

• I agree to follow the PSF Code of Conduct