Fixing more spelling errors (#16926)
## Summary
Here I fix the last English spelling errors I could find in the repo.
Again, I am trying not to touch variable/function names, or anything
that might be misspelled in the API. The goal is to make this PR safe
and easy to merge.
## Test Plan
I have run all the unit tests. Though, again, all of the changes I make
here are to docs and docstrings. I make no code changes, which I believe
should greatly mitigate the testing concerns.
