Add disclaimer to docs

layouts/_post.slim

@@ -1,5 +1,5 @@
 article
-  h1 == link_to @post[:title], @post.identifier.chop
   - time = Time.parse(@post[:created_at])
   date title=time.strftime('%F %R %Z') datetime=time.strftime('%FT%T%:z') pubdate=true = time.strftime('%B %-d, %Y')
+  h1 == link_to @post[:title], @post.identifier.chop
   == @content || @post.compiled_content

layouts/doc.slim

@@ -3,9 +3,9 @@ html lang='en'
   head == render '_head'
   body
     == render '_navbar'
-    .container
+    .container.doc
       .row
-        .span2.doc-nav
+        .span2
           ul.nav.nav-list.well
             li.nav-header Tent
             li == nav_link_with_active 'Protocol Introduction', '/docs'
@@ -21,5 +21,13 @@ html lang='en'
             li == nav_link_with_active 'Conversation', '/docs/example-conversation'
             li == nav_link_with_active 'Conversation Thread', '/docs/example-conversation-thread'
         .span8
+          .alert.alert-block
+            h4 Alpha Documentation 
+            p These docs are very rough, incorrect, and incomplete. They will be modified heavily over the next few weeks.
+            p
+              ' Please contribute by making Pull Requests and Issues on the
+              == link_to 'GitHub repository', 'https://github.com/tent/tent.io'
+              | .
+
           == yield
     == render '_footer'