Basically what this does is remind you to buy pots / food / flasks whenever you are in Dalaran / Stormwind.
I was too lazy to include every class hall, but you can easily include yours by just adding it to the group loading triggers (Zone ID).
The WA will only load if you're in these zones & out of combat.
No screenshot because it only displays text.
You'll get warnings if you don't have at least:
More than 25 Potions of Prolonged Power (Warning: LOW ON POTS!)
More than 20 of any of the 375 Legion foods (Warning: LOW ON FOOD!)
More than 5 of any of the Legion flasks (Warning: LOW ON FLASKS!)
You can easily change the requirements by fiddling around with the triggers.
Note that each of these categories has it's own warning, so there are 3 different ones in total (food, flask, pots).