doc: Coccinelle: move to HTML doc

Move doc/README.coccinelle to doc/develop/coccinelle.rst using the current
linux-next version of the text.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/doc/develop/index.rst b/doc/develop/index.rst
index eb5095a..98a95ad 100644
--- a/doc/develop/index.rst
+++ b/doc/develop/index.rst
@@ -7,5 +7,6 @@
 .. toctree::
    :maxdepth: 2
 
+   coccinelle
    crash_dumps
    logging