Added introduction

Change-Id: I06eb14895c6293160879e289c19902784bf66279
diff --git a/conf.py b/conf.py
index 6e16d1e..6dae38e 100644
--- a/conf.py
+++ b/conf.py
@@ -101,6 +101,11 @@
 # The name of the Pygments (syntax highlighting) style to use.
 pygments_style = None
 
+# Ignore link check for the following websites
+linkcheck_ignore = [
+    'https://www.opennetworking.org/trellis/',
+]
+
 # -- Options for HTML output -------------------------------------------------
 
 # The theme to use for HTML and HTML Help pages.  See the documentation for