feat(contact): mostly-complete contact page

re #32

contact.md

@@ -0,0 +1,20 @@
+---
+title: Contact — Apache OpenWhisk
+---
+
+The Dev Mailing List is where we discuss the development of Apache OpenWhisk. It is _not_ a place for technical support; if you're looking for help on a project, check out the [`#openwhisk` tag on Stack Overflow](http://stackoverflow.com/questions/tagged/openwhisk).
+
+### How to join the Apache OpenWhisk mailing list.
+
+**NOTE:** Make sure you add a subject line to the subscribe/unsubscribe messages. Empty emails are ignored.
+
+To subscribe to the list, send a message to:
+   <dev-subscribe@openwhisk.incubator.apache.org>
+
+To remove your address from the list, send a message to:
+   <dev-unsubscribe@openwhisk.incubator.apache.org>
+
+To create a new thread, send a message to:
+   <dev@openwhisk.incubator.apache.org>
+
+To comment on a thread, reply to the message.