Add a note about the transport specification (graphql#1209)

* Add a note about the transport specification

I'm seeing users and also the OSS community struggling at times to find the transport specification. Some have referred to this page in particular, so I'm hoping this leads them down the right path

* Update src/content/learn/BestPractice-ServingOverHTTP.md

Co-authored-by: Benjie <[email protected]>

Co-authored-by: Hugh Willson <[email protected]>
Co-authored-by: Benjie <[email protected]>

Author: 3 people

src/content/learn/BestPractice-ServingOverHTTP.md

@@ -82,4 +82,9 @@ app.use('/graphql', graphqlHTTP({
 ```
 
 ## Node
+
 If you are using NodeJS, we recommend looking at the [list of server implementations](/code/#javascript-server).
+
+## Draft Transport Specification
+
+A detailed [HTTP & websockets transport specification](https://github.com/graphql/graphql-over-http) is in development. Though it is not yet finalized, these draft specifications act as a single source of truth for GraphQL client & library maintainers, detailing how to expose and consume a GraphQL API using an HTTP transport. Unlike the language specification, adherence is not mandatory, but most implementations are moving towards these standards to maximize interoperability.