Problem: there are no events for invalid blocks (#2163)

Solution: update the documentation to reflect this. I've also removed
the documentation about the event plugin API. That part needs to be
refactored to work properly with BigchainDB 2.0. We can reintroduce it
later.

docs/server/source/events/index.rst

@@ -5,4 +5,3 @@ The Events API
     :maxdepth: 1
 
     websocket-event-stream-api
-    event-plugin-api

docs/server/source/events/websocket-event-stream-api.rst

@@ -11,7 +11,7 @@ The WebSocket Event Stream API
 BigchainDB provides real-time event streams over the WebSocket protocol with
 the Event Stream API.
 Connecting to an event stream from your application enables a BigchainDB node
-to notify you as events occur, such as new `validated transactions <#valid-transactions>`_.
+to notify you as events occur, such as new `valid transactions <#valid-transactions>`_.
 
 
 Demoing the API
@@ -26,7 +26,7 @@ Determining Support for the Event Stream API
 
 It's a good idea to make sure that the node you're connecting with
 has advertised support for the Event Stream API. To do so, send a HTTP GET
-request to the node's :ref:`api-root-endpoint` 
+request to the node's :ref:`api-root-endpoint`
 (e.g. ``http://localhost:9984/api/v1/``) and check that the
 response contains a ``streams`` property:
 
@@ -60,7 +60,7 @@ BigchainDB node will be ignored.
 
 Streams will always be under the WebSocket protocol (so ``ws://`` or
 ``wss://``) and accessible as extensions to the ``/api/v<version>/streams/``
-API root URL (for example, `validated transactions <#valid-transactions>`_
+API root URL (for example, `valid transactions <#valid-transactions>`_
 would be accessible under ``/api/v1/streams/valid_transactions``). If you're
 running your own BigchainDB instance and need help determining its root URL,
 then see the page titled :ref:`determining-the-api-root-url`.
@@ -70,22 +70,22 @@ All messages sent in a stream are in the JSON format.
 .. note::
 
     For simplicity, BigchainDB initially only provides a stream for all
-    validated transactions. In the future, we may provide streams for other
+    committed transactions. In the future, we may provide streams for other
     information. We may
     also provide the ability to filter the stream for specific qualities, such
     as a specific ``output``'s ``public_key``.
 
     If you have specific use cases that you think would fit as part of this
-    API, feel free to reach out via `Gitter <https://gitter.im/bigchaindb/bigchaindb>`_
-    or `email <mailto:product@bigchaindb.com>`_.
+    API, consider creating a new `BEP <https://github.com/bigchaindb/BEPs>`_.
 
 Valid Transactions
 ~~~~~~~~~~~~~~~~~~
 
 ``/valid_transactions``
 
-Streams an event for any newly validated transactions. Message bodies contain
-the transaction's ID, associated asset ID, and containing block's ID.
+Streams an event for any newly valid transactions committed to a block. Message
+bodies contain the transaction's ID, associated asset ID, and containing
+block's ID.
 
 Example message:
 
@@ -94,11 +94,11 @@ Example message:
     {
         "transaction_id": "<sha3-256 hash>",
         "asset_id": "<sha3-256 hash>",
-        "block_id": "<sha3-256 hash>"
+        "block_id": "<int>"
     }
 
 
 .. note::
 
-    Transactions in BigchainDB are validated in batches ("blocks") and will,
+    Transactions in BigchainDB are committed in batches ("blocks") and will,
     therefore, be streamed in batches.