Fix documentation of JVM server mode

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

@@ -76,12 +76,12 @@
 # WEB SERVER
 
 # Web server is executed in a dedicated Java process. By default its heap size is 768Mb.
-# Use the following property to customize JVM options. Enabling the HotSpot Server VM
-# mode (-server) is recommended.
+# Use the following property to customize JVM options.
+# The HotSpot Server VM is recommended. The property -server should be added if server mode
+# is not enabled by default on your environment: http://docs.oracle.com/javase/7/docs/technotes/guides/vm/server-class.html
 #sonar.web.javaOpts=-Xmx768m -XX:MaxPermSize=160m -XX:+HeapDumpOnOutOfMemoryError
 
-# Same as previous property, but allows to not repeat all other settings
-# like -Djava.awt.headless=true
+# Same as previous property, but allows to not repeat all other settings like -Xmx
 #sonar.web.javaAdditionalOpts=
 
 # Binding IP address. For servers with more than one IP address, this property specifies which
@@ -182,13 +182,14 @@
 # Elasticsearch is used to facilitate fast and accurate information retrieval.
 # It is executed in a dedicated Java process.
 
-# JVM options. Note that enabling the HotSpot Server VM mode (-server) is recommended.
+# JVM options
+# The HotSpot Server VM is recommended. The property -server should be added if server mode
+# is not enabled by default on your environment: http://docs.oracle.com/javase/7/docs/technotes/guides/vm/server-class.html
 #sonar.search.javaOpts=-Xmx1G -Xms256m -Xss256k -Djava.net.preferIPv4Stack=true \
 #  -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 \
 #  -XX:+UseCMSInitiatingOccupancyOnly -XX:+HeapDumpOnOutOfMemoryError
 
-# Same as previous property, but allows to not repeat all other settings
-# like -Djava.awt.headless=true
+# Same as previous property, but allows to not repeat all other settings like -Xmx
 #sonar.search.javaAdditionalOpts=
 
 # Elasticsearch port. Default is 9001. Use 0 to get a free port.