Fix case in configuration property

src/main/webapp/arsnova.properties.example

@@ -80,7 +80,7 @@ connector.username=test
 connector.password=test
 
 # Enable MathJax to allow the use of Math formulas written in TeX syntax in text fields.
-features.mathJax.enabled=true
+features.mathjax.enabled=true
 
 # The following features are considered experimental because they have not been
 # tested in a production environment over a longer time frame and/or their behavior

src/test/resources/arsnova.properties.example

@@ -80,7 +80,7 @@ connector.username=test
 connector.password=test
 
 # Enable MathJax to allow the use of Math formulas written in TeX syntax in text fields.
-features.mathJax.enabled=true
+features.mathjax.enabled=true
 
 # The following features are considered experimental because they have not been
 # tested in a production environment over a longer time frame and/or their behavior