Polishing MySQL / WordPress Tutorial (kubernetes#65)

* Polishing MySQL / WordPress Tutorial

* Readability Edits and Initial Comments from Ahmet

* Fix typo

* Update README.md

* Update README.md

* Revisions from Ahmet's Comments

PRs [kubernetes#66](kubernetes#66) and [kubernetes#67](kubernetes#67) update the manifest files with the new way to create the Secret.

* Prereq links

* Update mysql-deployment.yaml

* Update wordpress-deployment.yaml

Author: cody-clark