SONAR-2587 add a comment in conf/sonar.properties

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

@@ -86,6 +86,8 @@ sonar.jdbc.driverClassName:                org.apache.derby.jdbc.ClientDriver
 #sonar.jdbc.url:                            jdbc:postgresql://localhost/sonar
 #sonar.jdbc.driverClassName:                org.postgresql.Driver
 #sonar.jdbc.validationQuery:                select 1
+
+# If the PostgreSql database contains several schemas, the following property must define the schema to be used
 #sonar.jdbc.postgreSearchPath:              public