Update FUNDING.yml to include custom sponsorship link

Author: 0x676e67

.github/FUNDING.yml

@@ -3,7 +3,7 @@
 github: # Replace with up to 4 GitHub Sponsors-enabled usernames e.g., [user1, user2]
 patreon: # Replace with a single Patreon username
 open_collective: # Replace with a single Open Collective username
-ko_fi: '0x676e67'
+ko_fi:
 tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
 community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
 liberapay: # Replace with a single Liberapay username
@@ -12,4 +12,4 @@ lfx_crowdfunding: # Replace with a single LFX Crowdfunding project-name e.g., cl
 polar: # Replace with a single Polar username
 buy_me_a_coffee: # Replace with a single Buy Me a Coffee username
 thanks_dev: # Replace with a single thanks.dev username
-custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']
+custom: ['https://github.com/0x676e67/0x676e67/blob/main/SPONSOR.md']