add affiliate disclaimer

Author: tjhorner

docs/docs/01-build-guide/01-materials.md

@@ -4,6 +4,10 @@ id: materials
 
 # Materials
 
+:::info Disclaimer
+The AliExpress links below are affiliate links, which means we get a cut of the sale at no cost to you. Any revenue received from these links goes towards hosting costs for our Transit Tracker API server; **we do not profit from them**. Thanks for your support!
+:::
+
 To follow this build guide, you'll need the following parts:
 
 | Qty | Item                            | Purchase                                                                                                                                                                                                                                                                                                  | Notes                                                |