Sections 1.3.5 and 1.3.6 misuse "reserve" word for "reserved" word.

[glennstreet]

In Sections 1.3.5 "Reserved Words" and 1.3.6 "Built-in Types" the term "reserve word" is repeatedly used. Per the Python docs (https://docs.python.org/3/reference/lexical_analysis.html#keywords), I believe that "reserved" is correct. Alternatively, you might want to use "keyword" or "keywords" as appropriate. I made this an issue rather than correcting each occurrence via PRs.