Update pump.md (openaps#1168)

* Update pump.md

Added a warning for pump users about sending pumps away for repairs due to pumps coming back with new firmware not compatible with APS.

* Update pump.md

Author: GlennCoco

docs/docs/Gear Up/pump.md

@@ -47,3 +47,7 @@ If you need to acquire a compatible pump, check CraigsList, ask around local or
 
 If you're buying a pump online, we recommend you ask the seller to confirm the firmware version of the pump. (You may also want to consider asking for a video of the pump with working functionality before purchasing.)
 
+## Word of warning: Pump repairs rendering pumps useless for looping
+
+If you need to send your pump away to Medtronic for repair, be aware that during the repair process the firmware will get upgraded. This makes your pump not usable for looping. Ask the community if you run into a pump error - the community has tips for solving several common pump errors.
+