docs/devel: fix stable process doc formatting

Enumeration of stable criteria needs proper bullet points.

Message-Id: <20200113103023.31255-1-cohuck@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NCornelia Huck <cohuck@redhat.com>

docs/devel/stable-process.rst

@@ -18,8 +18,10 @@ What should go into a stable release?
 -------------------------------------
 
 Generally, the following patches are considered stable material:
-- Patches that fix severe issues, like fixes for CVEs
-- Patches that fix regressions
+
+* Patches that fix severe issues, like fixes for CVEs
+
+* Patches that fix regressions
 
 If you think the patch would be important for users of the current release
 (or for a distribution picking fixes), it is usually a good candidate