Fix README markdown to align to github standard.

The local markdown editor I use has a few quirks that deviate from
the markdown parser used by the one Github uses to display the README
for its projects.

Notably, my local editor doesn't recognize a code snippet based on the
indenting-four-spaces convention.  Because of this, several code
snippets were indented, as well as separated by triple-backticks (```).

This was causing a few small parsing hiccups on githubs end, and the
backticks were appearing in the README, rather than being taken for
escape characters.

Hopefully this commit fixes the issue by removing the backtick
characters.  It's hard to know for sure without pushing though, as I
don't know how to preview github's markdown parsing without pushing
this commit.