docs: create a new dev-tools directory

This directory will be a collecting point for documentation oriented around
development tools.  As a step toward ordering Documentation/ it's a small
one, but we have to start somewhere...

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/index.rst b/Documentation/index.rst
index e0fc729..643fb32 100644
--- a/Documentation/index.rst
+++ b/Documentation/index.rst
@@ -14,6 +14,7 @@
    :maxdepth: 2
 
    kernel-documentation
+   dev-tools/tools
    media/media_uapi
    media/media_kapi
    media/dvb-drivers/index