gh-37346: `sage.schemes.generic`: fix docs
Fix various docs problems.
I also removed the `SchemeRationalPoint` class entirely since it is not
used anywhere in the entire Sage library. If anyone oppose this please
notify me!
URL: https://github.com/sagemath/sage/pull/37346
Reported by: grhkm21
Reviewer(s): Kwankyu Lee
Committer
Release Manager