Add small messaging protocol description

Protocol.md

@@ -0,0 +1,32 @@
+# Hole Protocol
+
+## Process of messaging
+Each user have kind of a bin among freenet network,in which anyone can put message. And for each user this bin is his `USK insert` key. Each message signed by sender. And user can answer to sender, buy putting message at sender insert key if he know it.
+
+## Message request
+To receive a new message we have to send `ClientGet` to our `USK request` key with URI like `/user_id-message_version`. As well, the identifier is consists of  `user_id-message_number`
+For example:
+```Bash
+ClientGet
+URI=USK@myMessageBinKey/messages/user5678-3 
+Identifier=request-user5678-3
+Verbosity=0
+ReturnType=direct
+EndMessage
+```
+
+## Message sending
+To send a message to a friend we putting it at his `USK insert` key, with URI like`/my_id-$(number_of_messages_to_this_user + 1)`. And identifier like `user_id-$(number_of_messages_to_this_user + 1)`
+For example:
+
+```Bash
+ClientGet
+URI=USK@myFriendBinKey/messages/user3246-5
+Identifier=user3501-5
+Verbosity=0
+ReturnType=direct
+EndMessage
+```
+
+## user IDs
+- [ ] Probably, for each pair of each people we will have different identifier but... I'm not going to do it in further releases. *TODO*