remove Documentation/index.rst.rej

It got added accidentally by a previous patch that I had to "hand
apply".
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/index.rst.rej

---- Documentation/index.rst
-+++ Documentation/index.rst
-@@ -103,6 +103,7 @@ needed).
-    vm/index
-    bpf/index
-    PCI/index
-+   usb/index
-    misc-devices/index
- 
- Architecture-specific documentation