Write a friendly README.

README.md

@@ -1,3 +1,33 @@
 Client for the [Sugoma's RAC protocol](https://bedohswe.eu.org/text/rac/protocol.md.html).
 
-There's no help, figure everything out by yourself.
+
+Usage: ./dobroho_vechora.bash <MODE> <IP> <PORT> [NICK]
+
+
+Modes:
+
+* send: Reads the message from stdin and send it to the server.
+
+* receive: Writes the message buffer from the server to stdout.
+
+* interactive: Waits on stdin for lines with commands.
+
+
+Available commands:
+
+* I: Calls the editor (from VISUAL variable, if unset EDITOR is used. If both unset vi is used) and send the message if it is not empty.
+
+* i: Send the next string from stdout
+
+* L: Ask the server for current chat buffer's length.
+
+* l: Print current chat buffer's length.
+
+* w: Poll the server for new messages, print the chat buffer when they appear and execute the command specified by "DOBROHO_VECHORA_ON_WAIT" environment variable.
+
+* p: Print the chat buffer.
+
+* q: Exit.
+
+
+Client prints "?" on unknown commands.