Help Coccinelle a tiny bit more

It currently freaks out when it's not aware of a type, or when it
encounters v_*_ macros in a function signature. This doesn't improve the
results of the existing patches but we should take a habit of specifying
where additional C includes are.

tools/coccinelle/README.rst

@@ -6,6 +6,6 @@ for both the in-tree code style or out-of-tree VMOD and VUT development.
 
 Unless noted otherwise, all patches should work when invoked as::
 
-	spatch --dir . --in-place --sp-file $COCCI
+	spatch -I include/ -I bin/varnishd/ --dir . --in-place --sp-file $COCCI
 
 .. _coccinelle: http://coccinelle.lip6.fr/