Expand $wgDBDefaultGroup documentation

Per Krinkle's comment:
https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/440022/2/includes/DefaultSettings.php

Change-Id: I94e6e7f5048de610d2ae0722cb3de216288ed182

diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 8b25672..3771df1 100644 (file)
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -1892,6 +1892,8 @@ $wgDBmwschema = null;
 
 /**
  * Default group to use when getting database connections.
+ * Will be used as default query group in ILoadBalancer::getConnection.
+ * @since 1.32
  */
 $wgDBDefaultGroup = null;