qtvcp -docs: little spelling fix and better informing title

Author: c-morley

docs/src/gui/qtvcp.adoc

@@ -232,7 +232,7 @@ State_LED #name_of_led{
   }
 ----
 
-==== Handler Patching
+==== Handler Patching - Subclassing Builtin Screens
 We can have QtVCP load a subclassed version of the standard handler file. in that file we can manipulate the original functions or add new ones. +
 Subclassing just means our handler file first loads the original handler file and adds our new code on top of it - so a patch of changes. +
 This is useful for changing/adding behaviour while still retaining standard handler updates from LinuxCNC repositories. +
@@ -242,7 +242,7 @@ See 'custom handler file'
 
 There should be a folder in the config folder; for screens: named '<CONFIG FOLDER>/qtvcp/screens/<SCREEN NAME>/' +
 add the handle patch file there, named like so <ORIGINAL SCREEN NAME>_handler.py +
-ie for Qtdragon the file would be caller 'qtdragon_handler.py' +
+ie for Qtdragon the file would be called 'qtdragon_handler.py' +
 
 Here is a sample to add X axis jog pins to a screen like Qtdragon: +