Add initial (unfinished) protocol docs

docs/protocol.md

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+# systemquery protocol
+This document details the protocol implemented by systemquery. The protocol has multiple layers to it - these are documented each in their own sections:
+
+1. Framed transport
+2. Encryption
+3. JSON messages
+	- Also handles key exchange
+
+The protocol aims to have the following properties:
+
+ - It's peer-to-peer
+ - It's decentralised (i.e. there's no leading peer)
+	 - This may change in the future if there's a need for a leading peer
+ - It follows existing established standards where possible
+ - All communication is encrypted
+ - In order to join, peers must know the same join secret (aka a pre-shared key)
+ - In the future, full mesh network routing
+
+The following properties are out-of-scope:
+
+ - Tolerate malicious nodes
+
+
+## Framed Transport
+
+
+## JSON messages
+JSON messages look like this:
+
+```json
+{
+	"event": "EVENT_NAME",
+	"message": { "message_object": "here" }
+}
+```
+
+The following event names and their associated message objects are listed below:
+
+### Event `query`
+The sender requests a table from the receiver.
+
+Properties:
+
+ - **string `name`:** The name of the table being requested.
+
+### Event `query-response`
+The send response to the receiver's earlier `query` message.
+
+Properties:
+
+ - **string `name`:** The name of the table.
+ - **object `table`:** The requested table.