Fixes link to manual in bold section.

Nested inline markup is not possible at the moment, see
http://stackoverflow.com/a/9645684/172690. Maybe this would be a useful
extension to have in nimrod's custom rst engine?
Adds missing ``s`` to sligthly odd sentence.
Merge pull request #717 from gradha/pr_fixes_minor_doc_mistakes

Fixes minor doc mistakes.