Fix formatting in CONTRIBUTING.md (#6704)

Fix formatting in CONTRIBUTING.md

CONTRIBUTING.md

@@ -1,4 +1,4 @@
-# Filing an issue
+# Filing an issue
 
 ### Must read
 * If you aren't sure, you can ask on the [**forum**](http://forum.qbittorrent.org) or read our [**wiki**](http://wiki.qbittorrent.org) first.
@@ -11,7 +11,6 @@ Qt:
   libtorrent:
   boost:
   OS version:
-
   ```
 * Provide **steps** to reproduce the problem, it will be easier to pinpoint the fault.
 * **Screenshots**! A screenshot is worth a thousand words. just upload it. [(How?)](https://help.github.com/articles/file-attachments-on-issues-and-pull-requests)