add teardown instructions

Author: brianamarie

responses/teardown-instructions.md

@@ -1 +1,4 @@
-Hey, now we're gonna tear down the env...
+Now that we've had our fun, you may want to teardown your Azure environment to prevent any unexpected charges.
+
+1. Within your Azure Portal, navigate to the **probot-applications** resource group.
+2. Delete that resource group. (You will be asked to verify that you want to do this, by typing in the name of the resource.)