Add usage statements

Author: PatAltimore

articles/iot-operations/manage-mqtt-broker/howto-configure-availability-scale.md

@@ -171,6 +171,8 @@ There are predefined memory profiles with different memory usage characteristics
 
 ### Tiny
 
+Use this profile when you need to handle a small number of connections and messages and have limited memory resources.
+
 When using this profile:
 
 - Maximum memory usage of each frontend replica is approximately 99 MiB but the actual maximum memory usage might be higher.
@@ -183,6 +185,8 @@ Recommendations when using this profile:
 
 ### Low
 
+Use this profile when you need to handle a low number of connections and messages.
+
 When using this profile:
 
 - Maximum memory usage of each frontend replica is approximately 387 MiB but the actual maximum memory usage might be higher.