Fix links in documentation

Made links relative for GitHub compatibility.

src/site/markdown/development.md

@@ -14,7 +14,7 @@ And additionally if you want to run ARSnova locally:
 * [ARSnova Setup Tool](https://github.com/thm-projects/arsnova-setuptool)
 
 Next, you need to setup an ARSnova configuration file.
-Create a copy of [arsnova.properties.example](src/main/resources/arsnova.properties.example) at `/etc/arsnova/arsnova.properties`.
+Create a copy of [arsnova.properties.example](../../main/resources/arsnova.properties.example) at `/etc/arsnova/arsnova.properties`.
 Afterwards, initialize the database by running the `tool.py` python script from the Setup Tool.
 
 

src/site/markdown/upgrade.md

@@ -28,7 +28,7 @@ Unpack the downloaded archive and run the following commands in the extracted di
 ## Configuration Changes
 
 New ARSnova releases might introduce new configuration options or modify existing ones.
-We suggest you review the corresponding [arsnova.properties.example](src/main/resources/arsnova.properties.example) for your target version and adjust `/etc/arsnova.properties` accordingly.
+We suggest you review the corresponding [arsnova.properties.example](../../main/resources/arsnova.properties.example) for your target version and adjust `/etc/arsnova.properties` accordingly.
 
 
 ## Backend Upgrade