VERIFY_HEADER_SETS: Clarify that header sets must be PUBLIC or INTERFACE

Help/prop_tgt/VERIFY_HEADER_SETS.rst

@@ -8,14 +8,15 @@ their own.
 
 When this property is set to true, and the target is an object library, static
 library, shared library, or executable with exports enabled, and the target
-has one or more header sets, an object library target named
-``<target_name>_verify_header_sets`` is created. This verification target has
-one source file per header in the header sets. Each source file only includes
-its associated header file. The verification target links against the original
-target to get all of its usage requirements. The verification target has its
-:prop_tgt:`EXCLUDE_FROM_ALL` and :prop_tgt:`DISABLE_PRECOMPILE_HEADERS`
-properties set to true, and its :prop_tgt:`AUTOMOC`, :prop_tgt:`AUTORCC`,
-:prop_tgt:`AUTOUIC`, and :prop_tgt:`UNITY_BUILD` properties set to false.
+has one or more ``PUBLIC`` or ``INTERFACE`` header sets, an object library
+target named ``<target_name>_verify_header_sets`` is created. This verification
+target has one source file per header in the ``PUBLIC`` and ``INTERFACE``
+header sets. Each source file only includes its associated header file. The
+verification target links against the original target to get all of its usage
+requirements. The verification target has its :prop_tgt:`EXCLUDE_FROM_ALL` and
+:prop_tgt:`DISABLE_PRECOMPILE_HEADERS` properties set to true, and its
+:prop_tgt:`AUTOMOC`, :prop_tgt:`AUTORCC`, :prop_tgt:`AUTOUIC`, and
+:prop_tgt:`UNITY_BUILD` properties set to false.
 
 If the header's :prop_sf:`LANGUAGE` property is set, the value of that property
 is used to determine the language with which to compile the header file.