DocStyle description added rules for headings

DocStyle.md

@@ -22,7 +22,8 @@ Guidelines for Documentation Contributors
    where appropriate.
  * Use `[reference-style][ref]` links.
    `[ref]: http://daringfireball.net/projects/markdown/syntax#link`
-
+ * Use underline headings `=====` and `-----` if possible. If this is not
+   possible use the Atx-style headings on the left side, e. g. `### H3`.
 
 Sending documentation updates
 -----------------------------

ResizeRootDiskImage.md

@@ -5,7 +5,8 @@ permalink: /doc/ResizeRootDiskImage/
 redirect_from: /wiki/ResizeRootDiskImage/
 ---
 
-### Resizing \`root.img\` Size
+Resizing \`root.img\` Size
+--------------------------
 
 The safest way to increase the size of \`root.img\` is to do it for a standalone
 VM (qvm-create --standalone) - which has its own root filesystem
@@ -14,7 +15,7 @@ But it should also work for a normal template (as long as changes in the
 template between reboots didn't exceed 10G).
 
 Replace the size and the path (name) of the template as wished and run your
-modified command: 
+modified command:
 ```
 truncate -s 20G /var/lib/qubes/vm-templates/fedora-21/root.img
 ```