Update Cached Table example meta-data

Drop "Example" from the example's title, add SQL instead, and add it
to the Input/Output category of examples. It's a documented example,
does something meaningful, and looks reasonable. Having one SQL example
categorised so that it's easy to see that Qt includes that functionality
seems like a good idea. The other examples are mostly small API
examples that are still good to have as fully-functional apps rather
than just snippets.

Change-Id: Ib960f38db39c791f7ff5a2b9bf3157ee32b362ec
Reviewed-by: Andreas Eliasson <andreas.eliasson@qt.io>
(cherry picked from commit 8fa28b0cff8f06a7c266f2a6ff2a016daf4ad6d3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

examples/sql/doc/src/cachedtable.qdoc

@@ -3,8 +3,9 @@
 
 /*!
     \example cachedtable
-    \title Cached Table Example
+    \title Cached SQL Table
     \ingroup sql_examples
+    \examplecategory {Input/Output}
 
     \brief The Cached Table example shows how a table view can be used to access a database,
     caching any changes to the data until the user explicitly submits them using a

src/sql/models/qsqltablemodel.cpp

@@ -205,7 +205,7 @@ bool QSqlTableModelPrivate::exec(const QString &stmt, bool prepStatement,
     want to resolve foreign keys.
 
     \sa QSqlRelationalTableModel, QSqlQuery, {Model/View Programming},
-        {Table Model Example}, {Cached Table Example}
+        {Table Model Example}, {Cached SQL Table}
 */
 
 /*!