Help/dev: Exclude this directory from user-facing documentation

Teach Sphinx and our own install rules to skip a `Help/dev` directory.
This will give us a place to put developer-only documentation that
should not be included in the user-facing documentation.  Add a
placeholder README.

CMakeLists.txt

@@ -806,6 +806,7 @@ 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
     )
 
   # Install auxiliary files integrating with other tools.

Help/dev/README.rst

@@ -0,0 +1,15 @@
+CMake Development
+*****************
+
+This directory contains documentation about development of CMake itself.
+It is not part of the user documentation distributed with CMake.
+
+Contributor Instructions
+========================
+
+See `CONTRIBUTING.rst`_ for instructions to contribute changes.
+
+The process for contributing changes is the same whether or not one
+has been invited to participate directly in upstream development.
+
+.. _`CONTRIBUTING.rst`: ../../CONTRIBUTING.rst

Utilities/Sphinx/conf.py.in

@@ -18,7 +18,9 @@ release = '@conf_release@' # full version string
 
 primary_domain = 'cmake'
 
-exclude_patterns = []
+exclude_patterns = [
+    'dev', # ignore developer-only documentation
+    ]
 
 extensions = ['cmake']
 templates_path = ['@conf_path@/templates']