Add `embed_url` to the api docs (#14813)

Add embed_url to the api docs (#14813)

When creating a topic via the api you can pass in the embed_url param, so adding this to the api docs.

See: Add embed_url to topic create method by aaronpk · Pull Request #26 · discourse/discourse_api_docs · GitHub

diff --git a/spec/requests/api/schemas/json/topic_create_request.json b/spec/requests/api/schemas/json/topic_create_request.json
index c9a822e..70b1a44 100644
--- a/spec/requests/api/schemas/json/topic_create_request.json
+++ b/spec/requests/api/schemas/json/topic_create_request.json
@@ -33,10 +33,13 @@
     },
     "created_at": {
       "type": "string"
+    },
+    "embed_url": {
+      "type": "string",
+      "description": "Provide a URL from a remote system to associate a forum topic with that URL, typically for using Discourse as a comments system for an external blog."
     }
   },
   "required": [
     "raw"
   ]
 }
-

GitHub sha: 892e33fd93225b0913e7403d9328ed30e331e7b6

This commit appears in #14813 which was approved by martin. It was merged by blake.