Minor writing corrections

[awickert]

Small spelling and grammar changes; easier to provide my input this way than via a set of "issues".

[KevinShook]

Thanks for catching these. I have added all of these suggestions except for the first
as measurements appear to be singular when used in scientific writing, see
https://www.aje.com/arc/editing-tip-singular-and-plural-verbs-measured-quantities/