Modules/Documentation: remove

This is an old module from when VTK and other Kitware projects drove the
addition of commands and modules into CMake itself. Modern VTK doesn't
need this module and it can be ignored.

This module is kept around so that the ancient VTK versions which use it
are not broken by it. VTK itself stopped using the module in 2012 and
the last usage by an example in VTK was removed in 2020.

Fixes: #20591

1 files changed, 19 insertions, 0 deletions

diff --git a/Help/policy/CMP0106.rst b/Help/policy/CMP0106.rst
new file mode 100644
index 0000000..e34d15a
--- /dev/null
+++ b/Help/policy/CMP0106.rst
@@ -0,0 +1,19 @@
+CMP0106
+-------
+
+The :module:`Documentation` module is removed.
+
+The :module:`Documentation` was added as a support mechanism for the VTK
+project and was tuned for that project. Instead of CMake providing this module
+with (now old) VTK patterns for cache variables and required packages, the
+module is now deprecated by CMake itself.
+
+The ``OLD`` behavior of this policy is for :module:`Documentation` to add
+cache variables and find VTK documentation dependent packages. The ``NEW``
+behavior is to act as an empty module.
+
+This policy was introduced in CMake version 3.18.  CMake version |release|
+warns when the policy is not set and uses ``OLD`` behavior. Use the
+:command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly.
+
+.. include:: DEPRECATED.txt