Prefer typographic single quotes instead of straight double quotes.
This avoids confusion when double quotes are used as part of arguments.
Annotate EOF as a "defined variable".
Assuming mandoc is used, `apropos Dv=EOF` should now work.
Clarify in parentheses what a hyphen is, as users might only know it
as a "dash". The same was already done for colons.
Group environment variables more logically.
Reviewed-by: Felipe Morales <hel.sheep@gmail.com>
Reviewed-by: Ian Ker-Seymer <i.kerseymer@gmail.com>