minor: build error

Author: Sam Kleinman

source/release-notes/2.2.txt

@@ -156,11 +156,11 @@ Improved Data Center Awareness with Tag Aware Sharding
 
 MongoDB 2.2 adds additional support for geographic distribution or
 other custom partitioning for sharded collections in :term:`shard
-clusters`.  By using this "tag aware" sharding, you can automatically
-ensure that data in a sharded database system is always on specific
-shards. For example, with tag aware sharding, you can ensure that data
-is closest to the application servers that use that data most
-frequently.
+clusters <shard cluster>`.  By using this "tag aware" sharding, you
+can automatically ensure that data in a sharded database system is
+always on specific shards. For example, with tag aware sharding, you
+can ensure that data is closest to the application servers that use
+that data most frequently.
 
 Shard tagging controls data location, and is complementary but
 separate from replica set tagging, which controls :ref:`read