materialization: Add message action and additional fields to feature …

…documentation

- Added @action@ enum field in the message structure, which specifies the type of the message action. It includes a series of predefined actions (CREATE, UPDATE, DELETE, etc.).
- Added additional fields `serial`, `refSerial`, `refType`, `updatedAt`, `deletedAt`, and `operation` to the Message data type.
- Update the Message class to reflect the new members.
- Added section on REST and Realtime publish that now requires the message action field to be set on publish.

textile/features.textile

@@ -1305,6 +1305,16 @@ h4. Message
 ** @(TM2e)@ @encoding@ string
 ** @(TM2i)@ @extras@ JSON-encodable object, used to contain any arbitrary key value pairs which may also contain other primitive JSON types, JSON-encodable objects or JSON-encodable arrays. The @extras@ field is provided to contain message metadata and/or ancillary payloads in support of specific functionality, e.g. push. Each of these supported extensions is documented separately; for 1.1 the only supported extension is @push@, via the @extras.push@ member; 1.2 adds the @delta@ extension whose keys and values are described by the attributes of the type @DeltaExtras@, and the @headers@ extension, which contains arbitrary @string->string@ key-value pairs, settable at publish time, and @ref@ whose keys and values are described by the attributes of the type @ReferenceExtras@. Unless otherwise specified, the client library should not attempt to do any filtering or validation of the @extras@ field itself, but should treat it opaquely, encoding it and passing it to realtime unaltered.
 ** @(TM2f)@ @timestamp@ time in milliseconds since epoch. If a message received from Ably does not contain a @timestamp@, it should be set to the @timestamp@ of the encapsulating @ProtocolMessage@
+** @(TM2j)@ @action@ enum
+** @(TM2K)@ @serial@ string - an opaque string that uniquely identifies the message.
+** @(TM2L)@ @refSerial@ string - an opaque string that uniquely identifies some referenced message.
+** @(TM2M)@ @refType@ string - an opaque string that identifies the type of this reference.
+** @(TM2N)@ @updatedAt@ time in milliseconds since epoch. This field is always populated on messages received with an @action@ of @MESSAGE_UPDATE@.
+** @(TM2O)@ @deletedAt@ time in milliseconds since epoch. This field is always populated on messages received with an @action@ of @MESSAGE_DELETE@.
+** @(TM2P)@ @operation@ optional object that may contain the following `optional` attributes;
+*** @(TM2P1)@ @clientId@ string
+*** @(TM2P2)@ @description@ string
+*** @(TM2P3)@ @metadata@ object - used to contain any arbitrary key value pairs of type string.
 * @(TM4)@ @Message@ has constructors @constructor(name: String?, data: Data?)@ and @constructor(name: String?, data: Data?, clientId: String?)@.
 * @(TM3)@ @fromEncoded@ and @fromEncodedArray@ are alternative constructors that take an (already deserialized) @Message@-like object (or array of such objects), and optionally a @channelOptions@, and return a @Message@ (or array of such @Messages@) that's decoded and decrypted as specified in @RSL6@, using the cipher in the @channelOptions@ if the message is encrypted, with any residual transforms (ones that the library cannot decode or decrypt) left in the @encoding@ property per @RSL6b@. This is intended for users receiving messages other than from a REST or Realtime channel (for example, from a queue), to avoid them having to parse the @encoding@ string themselves.
 
@@ -2130,6 +2140,17 @@ enum PresenceAction: // TP2
   LEAVE // TP2
   UPDATE // TP2
 
+enum MessageAction: // TM5
+    MESSAGE_UNSET // TM5
+    MESSAGE_CREATE // TM5
+    MESSAGE_UPDATE // TM5
+    MESSAGE_DELETE // TM5
+    ANNOTATION_CREATE // TM5
+    ANNOTATION_DELETE // TM5
+    META_OCCUPANCY // TM5
+
+
+
 class ConnectionDetails: // CD*, internal
   clientId: String? // RSA12a, CD2a
   connectionKey: String // RTN15e, CD2b
@@ -2154,6 +2175,13 @@ class Message: // TM*
   id: String // TM2a
   name: String? // TM2g
   timestamp: Time // TM2f
+  action: MessageAction // TM2j
+  serial: string // TM2K
+  refSerial: string? // TM2L
+  refType: string? // TM2M
+  updatedAt: Time? // TM2N
+  deletedAt: Time? // TM2O
+  operation: JsonObject? // TM2P
 
 class PresenceMessage // TP*
   +fromEncoded(JsonObject, ChannelOptions?) -> PresenceMessage // TP4