Update FUNDING.yml

.github/FUNDING.yml

@@ -11,4 +11,4 @@ issuehunt: # Replace with a single IssueHunt username
 otechie: # Replace with a single Otechie username
 lfx_crowdfunding: # Replace with a single LFX Crowdfunding project-name e.g., cloud-foundry
 polar: # Replace with a single Polar username
-custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']
+custom: ['https://steamcommunity.com/tradeoffer/new/?partner=41515647&token=gW2W-nXE'] # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']