update URI

Author: hugohn

bip-0129.mediawiki

@@ -8,7 +8,7 @@
           Aaron Chen <[email protected]>
           Rodolfo Novak <[email protected]>
   Comments-Summary: No comments yet.
-  Comments-URI:
+  Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0129
   Status: Proposed
   Type: Standards Track
   Created: 2020-11-10