Fix license subheading size

Author: stgeneral

README.md

@@ -49,7 +49,8 @@ Proressive plugins for Redmine
 * [Progressive Gantt Mods](http://stgeneral.github.io/redmine-progressive-gantt-mods/) - assignee column and some preferences for Gantt chart.
 * [Collapsed Journals Plugin](https://github.com/stgeneral/redmine-collapsed-journals) - collapses issue history items without an assosiated note
 
-### License ###
+License
+-------
 
 *The MIT License (MIT)*