Clarify prompt instructions for so-elastalert-test

salt/common/tools/sbin/so-elastalert-test

@@ -96,7 +96,7 @@ rule_prompt(){
 	echo "-----------------------------------"
 	echo
 	while [ -z "$RULE_NAME" ]; do
-		read -p "Please enter the rule filename you want to test (filename only, no path): " -e RULE_NAME
+		read -p "Choose a rule to test from the list above (must be typed exactly as shown above): " -e RULE_NAME
 	done
 }