Fix configuration documentation formatting

Change-Id: Ia194c648c0d0d0d1900778474aa8321a932336c4

src/main/resources/Documentation/config.md

diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index 69b7a46..19299d3 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md
@@ -4,12 +4,14 @@
 File 'gerrit.config'
 --------------------
 
+```
   [plugin "@PLUGIN@"]
     maxAge = 20
     returnLimit = 10000
     storeUrl = jdbc:h2:~/gerrit/db/
     urlOptions = DB_CLOSE_DELAY=10
     copyLocal = true
+```
 
 plugin.@PLUGIN@.maxAge
 :    Specify the maximum allowed age in days of the entries in the database.
@@ -68,4 +70,4 @@
 plugin.@PLUGIN@.evictIdleTime
 :    Interval of time in milliseconds after which an idle database connection is
      evicted from the connection pool. When not specified, the default value is
-     set to 60000ms.
\ No newline at end of file
+     set to 60000ms.