docs: Initial start on process design rules.

Updates and documentation originally improved and then release by
Kevin Kelly <kevin.kelley@skywatertechnology.com> to Google for imported
into the docutils RST format by Tim 'mithro' Ansell <tansell@google.com>.

Signed-off-by: Kevin Kelley <kevin.kelley@skywatertechnology.com>
Signed-off-by: Tim 'mithro' Ansell <tansell@google.com>
diff --git a/docs/index.rst b/docs/index.rst
index 4c3e657..53ea8f3 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -3,6 +3,8 @@
 .. toctree::
     :hidden:
 
+    Design Rules <rules>
+
     versioning
     Current Status <status>
     known_issues