Help: Document the CMAKE_PREFIX_PATH environment variable

Help/envvar/CMAKE_PREFIX_PATH.rst

@@ -0,0 +1,17 @@
+CMAKE_PREFIX_PATH
+-----------------
+
+.. include:: ENV_VAR.txt
+
+The ``CMAKE_PREFIX_PATH`` environment variable may be set to a list of
+directories specifying installation *prefixes* to be searched by the
+:command:`find_package`, :command:`find_program`, :command:`find_library`,
+:command:`find_file`, and :command:`find_path` commands.  Each command will
+add appropriate subdirectories (like ``bin``, ``lib``, or ``include``)
+as specified in its own documentation.
+
+This variable may hold a single prefix or a list of prefixes separated
+by ``:`` on UNIX or ``;`` on Windows (the same as the ``PATH`` environment
+variable convention on those platforms).
+
+See also the :variable:`CMAKE_PREFIX_PATH` CMake variable.

Help/manual/cmake-env-variables.7.rst

@@ -14,6 +14,13 @@ For general information on environment variables, see the
 :ref:`Environment Variables <CMake Language Environment Variables>`
 section in the cmake-language manual.
 
+Environment Variables that Change Behavior
+==========================================
+
+.. toctree::
+   :maxdepth: 1
+
+   /envvar/CMAKE_PREFIX_PATH
 
 Environment Variables that Control the Build
 ============================================