Add page explaining how to send template using API

Would like to test something like this and see how well it works.

Intention of having this page is so:
- template IDs are discoverable (https://www.pivotaltracker.com/story/show/115404593)
- it’s obvious there’s an ‘automated’ way to send messages, as well as the CSV
  way (we’ve seen people oblivious to this in research)

app/assets/stylesheets/app.scss

@@ -65,6 +65,7 @@ a {
 .highlight {
   font-family: monospace;
   overflow-x: scroll;
+  padding: 10px 0 10px 10px;
 }
 
 .inline {

app/assets/stylesheets/components/sms-message.scss

@@ -43,14 +43,8 @@
   margin-top: 52px;
 
   a {
-
     display: block;
     margin-bottom: 5px;
-
-    &:first-child {
-      @include bold-19;
-    }
-
   }
 
 }