Update landing pages spec.

Author: nateranson

spec/marketing.json

@@ -813,7 +813,7 @@
     },
     "swagger": "2.0",
     "info": {
-        "version": "3.0.83",
+        "version": "3.0.84",
         "title": "Mailchimp Marketing API",
         "contact": {
             "name": "Mailchimp API Support",
@@ -87745,7 +87745,7 @@
             },
             "post": {
                 "summary": "Add landing page",
-                "description": "Create a new Mailchimp landing page.",
+                "description": "Create an unpublished and contentless Mailchimp landing page.",
                 "parameters": [
                     {
                         "name": "body",