Adding contribution guidelines to user guide, including new Developer's Certificate of Origin
diff --git a/user_guide_src/source/index.rst b/user_guide_src/source/index.rst
index c89b41c..a349d8b 100644
--- a/user_guide_src/source/index.rst
+++ b/user_guide_src/source/index.rst
@@ -91,6 +91,17 @@
helpers/index
+***************************
+Contributing to CodeIgniter
+***************************
+
+.. toctree::
+ :glob:
+ :titlesonly:
+
+ contributing/index
+ DCO
+
.. toctree::
:glob:
:titlesonly: