Remove $ prefix from bash snippets

[ghost]

also fixes some minor inconsistencies

Closes #369

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @nikomatsakis (or someone else) soon.

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[styfle]

Thanks!

[nikomatsakis]

r? @skade -- can you reassign this to someone from the web site working group who is more qualified to judge it? Thanks!

(Seems good to me, fwiw)

[nikomatsakis]

Also, sorry for the delay in responding to the PR @BO41

[skade]

@nikomatsakis oddly, website group doesn't have access here ;)

[skade]

r+ from my side

[nikomatsakis]

@bors r+

[nikomatsakis]

Or I guess bors doesn't govern this, does it?

[styfle]

Thanks!