DOCS-1632: Clarify to which size metric the limit for sharding an existi...

source/reference/limits.txt

@@ -149,19 +149,14 @@ Sharded Clusters
 
 .. limit:: Sharding Existing Collection Data Size
 
-   When enabling sharding on an existing collection, MongoDB imposes a
-   maximum size on those collections to ensure that its possible to
-   create chunks. The precise size of the limitation is a function of
-   the chunk size and the data size: *MongoDB supports sharding all
-   collections smaller than 256 gigabytes.* You may be able to enable
-   sharding for existing collections between 256 and 400 gigabytes in
-   size, depending on the distribution of document sizes.
-
-   .. note::
-
-      This limitation *only* applies to sharding collections that have
-      existing data sets, and is *not* a limit on the size of a
-      sharded collection.
+   For existing collections, MongoDB supports enabling sharding on
+   collections that contain less than 256 gigabytes of data. MongoDB may
+   be able to shard collections with as many as 400 gigabytes depending
+   on the distribution of document sizes. The precise size of the
+   limitation is a function of the chunk size and the data size.
+
+   .. note:: Sharded collections may have *any* size, after successfully
+      enabling sharding.
 
 .. limit:: Single Document Modification Operations in Sharded Collections