Help: Add infrastructure for guide-level documentation

Create a `Help/guide/` directory to hold guide-level documents.
Build them in most documentation formats, but not as man pages.

Initialize the guide directory with a placeholder for the tutorial.

CMakeLists.txt

@@ -817,7 +817,7 @@ if(NOT CMake_TEST_EXTERNAL_CMAKE)
     PATTERN "*.sh*" PERMISSIONS OWNER_READ OWNER_EXECUTE OWNER_WRITE
                                 GROUP_READ GROUP_EXECUTE
                                 WORLD_READ WORLD_EXECUTE
-    REGEX "Help/dev($|/)" EXCLUDE
+    REGEX "Help/(dev|guide|index.rst)($|/)" EXCLUDE
     )
 
   # Install auxiliary files integrating with other tools.

Help/guide/tutorial/index.rst

@@ -0,0 +1,2 @@
+CMake Tutorial
+**************

Help/index.rst

@@ -44,6 +44,14 @@ Reference Manuals
    /manual/cmake-variables.7
    /manual/cpack-generators.7
 
+Guides
+######
+
+.. toctree::
+   :maxdepth: 1
+
+   /guide/tutorial/index
+
 .. only:: html or text
 
  Release Notes