Update Bash

- Markdown parser has issues with bolding something after parentheses.
  escaping the characters did not work so HTML was added.
- I took a poll of five people which concluded they would use the word "folders" in place of directories.
- Change meaning of [terminal](http://en.wikipedia.org/wiki/Computer_terminal).
- Add intro to `man` pages. :school: 
- Add reference to ExplainShell