SONAR-3212 Document format of conf/sonar.properties

sonar-application/src/main/assembly/conf/sonar.properties

@@ -1,4 +1,7 @@
 #--------------------------------------------------------
+# This file must contain only ISO 8859-1 characters and match format, which described in
+# http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Properties.html#load(java.io.InputStream)
+#
 # To use an environment variable, use the following syntax :  ${env:NAME_OF_ENV_VARIABLE}
 # For example :
 #   sonar.jdbc.url: ${env:SONAR_JDBC_URL}