fix(docs): add nitpick_ignores for stdlib classes
fix(docs): add nitpick_ignores for stdlib classes

Seems to be related to https://bugs.python.org/issue11975. Without these
`nitpick_ignore` statements, we get "py:class reference target not
found" errors on a handful of stdlib classes.

samstav/simpl,checkmate/simpl,ryandub/simpl,larsbutler/simpl