Update Schema.md

Changing URI to be in Metadata as per rsocket/rsocket#22

Author: benjchristensen

Schema.md

@@ -4,16 +4,13 @@ A default schema for use with ReactiveSocket.
 
 ### Version 0 – application/x.reactivesocket.v0+xxx
 
-#### Data
+#### Metadata
 
 Requests must contain fields used for routing:
 
 ```
 Key: uri [REQUIRED]
 Value: String
-
-Key: body [OPTIONAL]
-Value: Object
 ```
 
 Non-request types have no specific keys, just "Object" encoded in the specificed encoding (ie. JSON, CBOR, etc)
@@ -24,7 +21,7 @@ MimeTypes for the above schema:
 - application/x.reactivesocket.v0+cbor (schema above encoded with CBOR)
 
 
-#### Metadata
+#### Data
 
 There is no specific schema so it is expected to use JSON, CBOR, etc as is.