Help: Fix a typo in the AUTOGEN_SOURCE_GROUP help

Help/prop_gbl/AUTOGEN_SOURCE_GROUP.rst

@@ -9,7 +9,7 @@ Name of the  :command:`source_group` for :prop_tgt:`AUTOMOC` and
 Files generated by :prop_tgt:`AUTOMOC` and :prop_tgt:`AUTORCC` are not always
 known at configure time and therefore can't be passed to
 :command:`source_group`.
-:prop_gbl:`AUTOGEN_SOURCE_GROUP` an be used instead to generate or select
+:prop_gbl:`AUTOGEN_SOURCE_GROUP` can be used instead to generate or select
 a source group for :prop_tgt:`AUTOMOC` and :prop_tgt:`AUTORCC` generated files.
 
 For :prop_tgt:`AUTOMOC` and :prop_tgt:`AUTORCC` specific overrides see