Fix typo: "Contast" to "Contrast"
Added links to Flipper section

Signed-off-by: E.T.Cook <e@etc.io>
remove broken link
closes #168
fix simo's bug != false
Fixes #409
Example:
```
add_action( 'pl_get_author_tag', function() { echo '<p>[post_date]</p>'; } );
```
Merge pull request #420 from cliffordp/patch-10

Fix typo: "Contast" to "Contrast"
Merge pull request #438 from etcook/Dev

Added links to titles in Flipper section