Fix document alignment

Author: tim-ojo

README.md

@@ -6,13 +6,13 @@ There are certain concepts, algorithms or methods that you use infrequently enou
 
 Cheat Sheet is built on GitHub's Electron framework, so it runs on Windows, Linux and Mac OS X. 
 
-**Main Screen**
+###### Main Screen
 ![Main Screen](https://raw.githubusercontent.com/tim-ojo/cheat-sheet/master/docs/main_screen.png)
 
-**Adding or Editing a Cheat**
+###### Adding or Editing a Cheat
 ![Add or Edit Screen](https://raw.githubusercontent.com/tim-ojo/cheat-sheet/master/docs/add_or_edit.png)
 
-**Filtering with tags**
+###### Filtering with tags
 ![Tags](https://raw.githubusercontent.com/tim-ojo/cheat-sheet/master/docs/tags.png)
 
 ![Filtering](https://raw.githubusercontent.com/tim-ojo/cheat-sheet/master/docs/tags_filtered.png)