Reword the description of mbedtls_net_free()

This makes it clearer that the context itself is not being freed.

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/include/mbedtls/net_sockets.h b/include/mbedtls/net_sockets.h
index 14316fb..9f9e2ad 100644
--- a/include/mbedtls/net_sockets.h
+++ b/include/mbedtls/net_sockets.h
@@ -283,16 +283,16 @@
                              uint32_t timeout);
 
 /**
- * \brief          Closes down the connection and free associated data
+ * \brief          Close down the connection and clear the context
  *
  * \param ctx      The context to close
  */
 void mbedtls_net_close(mbedtls_net_context *ctx);
 
 /**
- * \brief          Gracefully shutdown the connection and free associated data
+ * \brief          Gracefully shutdown the connection and clear the context
  *
- * \param ctx      The context to free
+ * \param ctx      The context to gracefully shutdown
  */
 void mbedtls_net_free(mbedtls_net_context *ctx);