Use inline literal syntax to avoid turning hyphens to dashes

This commit changes some quoted strings to ``string`` from "string".

The rationale is that within "string" context, two hyphens become an em dash. Within ``string`` context, they stay hyphens. This is important for commands that could be copy-pasted, or that help people see what commands they should type into their own terminals.

This work is my own, and I grant permission to distribute this change under the terms of the CC Zero (i.e., I waive all copyright rights) or under the terms of Apache License 2.0; any redistributor is permitted to choose whichever (or both) terms to use.
Merge pull request #50 from paulproteus/patch-1

Use inline literal syntax to avoid turning hyphens to dashes