README: Linkify 'a defined format' & simplify plaintext/compression header

schemas/README-EDDN-schemas.md

@@ -3,13 +3,14 @@
 ## Introduction
 
 EDDN is a
-[zermoq](https://zeromq.org/) service to allow players of the game
+[zermoq](https://zeromq.org/) service which allows players of the game
 [Elite Dangerous](https://www.elitedangerous.com/), published
 by [Frontier Developments](https://www.frontier.co.uk/), to upload game data so
 that interested listeners can receive a copy.
 
-EDDN accepts HTTP POST uploads in a defined format representing this game data
-and then passes it on to any interested listeners.
+EDDN accepts HTTP POST uploads in
+[a defined format](#sending-data)
+representing this game data and then passes it on to any interested listeners.
 
 ---
 ## Sources
@@ -120,12 +121,9 @@ Messages sent to EDDN **MUST**:
 - Use a **POST** request, with the body containing the EDDN message.  No
   query parameters in the URL are supported or necessary.
 
-The body of an EDDN message is a JSON object in UTF-8 encoding.  You MUST
-set a `Content-Type` header of `applicaton/json`, and NOT any of:
-
-* `application/x-www-form-urlencoded`
-* `multipart/form-data`
-* `text/plain`
+The body of an EDDN message is a JSON object in UTF-8 encoding.  If you do not
+compress this body then you MUST set a `Content-Type` header of
+`applicaton/json`.
 
 For historical reasons URL form-encoded data *is* supported, **but this is 
 deprecated and no new software should attempt this method**.  We 
@@ -133,7 +131,7 @@ purposefully do not further document the exact format for this.
 
 You *MAY* use gzip compression on the body of the message, but it is not 
 required.  If you do compress the body then you **MUST* send a `Content-Type`
-header with `gzip` value instead of `application/json`.
+header of `gzip` instead of `application/json`.
 
 You should be prepared to handle all scenarios where sending of a message 
 fails: