first bot draft

README.md

@@ -61,6 +61,14 @@ use for querying.
 Log into your bot account with a XMPP client and add your personal JID to your roster.
 Querying will only work with a two-way subscription.
 
+## Bot usage
+
+From your personal account, send a normal chat message to your bot.
+Available commands:
+
+* `budgets` - list all budgets names
+* `budget <budget>` - query data for given budget
+
 ### Docker
 
 Run the prebuilt image: