Update schema router documentation

Documentation/Changelog.md

@@ -21,6 +21,7 @@
   * Transaction load balancing for normal transactions
   * Support for runtime router reconfiguration
 * Experimental resultset concatenation router, `cat`
+* The schema router is now capable of sharding tables.
 
 For more details, please refer to:
 

Documentation/Release-Notes/MaxScale-2.3.0-Release-Notes.md

@@ -205,6 +205,11 @@ for details.
 
 The `source` parameter can now contain a list of comma separated addresses.
 
+### Table Sharding
+
+The SchemaRouter is now capable of sharding tables. Please see the SchemaRouter
+[documentation](../Routers/SchemaRouter.md) for details.
+
 ### Interactive Mode for MaxCtrl
 
 ### ReadWriteSplit

Documentation/Routers/SchemaRouter.md

@@ -8,6 +8,9 @@ database-based sharding, the schemarouter router also enables cross-node
 session variable usage by routing all queries that modify the session to all
 nodes.
 
+From 2.3.0 onwards, the SchemaRouter is capable of sharding tables, in
+addition to sharding databases.
+
 ## Routing Logic
 
 If a command line client is used, i.e. `mysql`, and a direct connection to
@@ -114,6 +117,29 @@ refresh_databases=true
 refresh_interval=60
 ```
 
+## Table Sharding
+
+This functionality was introduced in 2.3.0.
+
+If the same database exists on multiple servers, but the database contains
+different tables in each server, the SchemaRouter is capable of
+transparently routing queries to the right server, depending on which table
+is being addressed.
+
+For instance, suppose the database `db` exists on servers _server1_ and
+_server2_, but that the database on _server1_ contains the table `tbl1` and
+on _server2_ contains the table `tbl2`.
+
+In that case, the query
+```
+SELECT * FROM db.tbl1
+```
+will be routed to _server1_ and the query
+```
+SELECT * FROM db.tbl2
+```
+will be routed to _server2_.
+
 ## Router Options
 
 **Note:** Router options for the Schemarouter were deprecated in MaxScale 2.1.