docs: Create a user-space API guide

This is meant to be the place for documentation relevant to application
developers.  It's empty for the moment, but at least we have a place now!

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/index.rst b/Documentation/index.rst
index f6e641a..12550cc 100644
--- a/Documentation/index.rst
+++ b/Documentation/index.rst
@@ -24,6 +24,18 @@
 
    admin-guide/index
 
+Application-developer documentation
+-----------------------------------
+
+The user-space API manual gathers together documents describing aspects of
+the kernel interface as seen by application developers.
+
+.. toctree::
+   :maxdepth: 2
+
+   userspace-api/index	      
+
+
 Introduction to kernel development
 ----------------------------------