Autogen: Update documentation for per-config include dir

Help/manual/cmake-qt.7.rst

@@ -72,6 +72,9 @@ Included ``moc_*.cpp`` and ``*.moc`` files will be generated in the
 automatically added to the target's :prop_tgt:`INCLUDE_DIRECTORIES`.
 (This differs from CMake 3.7 and below; see their documentation for details.)
 
+* For multi configuration generators, the include directory is
+  ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>``.
+
 * See :prop_tgt:`AUTOGEN_BUILD_DIR`.
 
 Not included ``moc_<basename>.cpp`` files will be generated in custom
@@ -117,6 +120,9 @@ The generated generated ``ui_*.h`` files are placed in the
 automatically added to the target's :prop_tgt:`INCLUDE_DIRECTORIES`.
 (This differs from CMake 3.7 and below; see their documentation for details.)
 
+* For multi configuration generators, the include directory is
+  ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>``.
+
 * See :prop_tgt:`AUTOGEN_BUILD_DIR`.
 
 The :prop_tgt:`AUTOUIC` target property may be pre-set for all following

Help/prop_tgt/AUTOMOC.rst

@@ -20,6 +20,9 @@ source files at build time and invoke moc accordingly.
   This allows the compiler to find the included ``moc_<basename>.cpp`` file
   regardless of the location the original source.
 
+  * For multi configuration generators, the include directory is
+    ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>``.
+
   * See :prop_tgt:`AUTOGEN_BUILD_DIR`.
 
 * If an ``#include`` statement like ``#include "<basename>.moc"`` is found,

Help/prop_tgt/AUTOUIC.rst

@@ -17,6 +17,9 @@ optional :prop_tgt:`AUTOUIC_SEARCH_PATHS` of the target.
 ``<AUTOGEN_BUILD_DIR>/include``,
 which is automatically added to the target's :prop_tgt:`INCLUDE_DIRECTORIES`.
 
+* For multi configuration generators, the include directory is
+  ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>``.
+
 * See :prop_tgt:`AUTOGEN_BUILD_DIR`.
 
 This property is initialized by the value of the :variable:`CMAKE_AUTOUIC`