Add documentation for the configuration
Change-Id: I2486859966430919fa1c08524e515798ba37c10a
diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
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+Graphite Metrics Reporter Configuration
+=======================================
+
+File `@PLUGIN@.config`
+-------------------------
+
+The optional file `$site_path/etc/@PLUGIN@.config` is a Git-style
+config file that controls the settings for the @PLUGIN@ plugin.
+
+graphite.host
+: Hostname of the Graphite server. Defaults to `localhost`.
+
+graphite.port
+: Port number of the Graphite server. Defaults to `2003`.
+
+graphite.prefix
+: Prefix to use when reporting metrics. Defaults to `gerrit.`
+ suffixed with the hostname of `localhost`.
