Fix config.md keys using @PLUGIN@ placeholder

The config.md contained incorrect key prefixes and
also did not use the @PLUGIN@ placeholder, leading
to misleading documentation.

Use the correct key values and allow a flexible naming
of the plugin, allowing other names to be reflected
in the rendering of config.md.

Change-Id: Ia2bab666a2091bfbb0cef8efa152df91b8d90d07
diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index a18a878..e60c678 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md
@@ -7,10 +7,10 @@
 The audit configuration can be defined in the main gerrit.config
 in a specific section dedicated to the audit-sl4j plugin.
 
-gerrit.audit-sl4j.format
+plugin.@PLUGIN@.format
 :	Output format of the audit record. Can be set to either JSON
     or CSV. By default, CSV.
     
-gerrit.audit-sl4j.logName
+plugin.@PLUGIN@.logName
 :	Write audit to a separate log name under Gerrit logs directory.
-    By default, audit records are put into the error_log.
\ No newline at end of file
+    By default, audit records are put into the error_log.