docs: add demo_batch_messages command and update readme with project description and setup instructions

Makefile

@@ -1,9 +1,10 @@
 DEMO_REPLIKA = .venv/bin/ragent.demo_replika 
 DEMO_DISCUSS = .venv/bin/ragent.demo_discuss 
+DEMO_BATCH_MESSAGES = .venv/bin/ragent.demo_batch_messages
 PIP = .venv/bin/pip 
 
 default:
-	@echo "Hi, there are two commands to run: demo_replika and demo_discuss."
+	@echo "Hi, there are three commands to run: demo_replika, demo_discuss and demo_batch_messages."
 	@echo "Before running these commands, you need to run 'make install'."
 
 install:
@@ -19,3 +20,7 @@ demo_replika:
 demo_discuss:
 	@echo "Executing Discussion Demo."
 	$(DEMO_DISCUSS)
+
+demo_batch_messages:
+	@echo "Executing Batch Messages Demo."
+	$(DEMO_BATCH_MESSAGES)