Update src/projects/zcash/index.yaml

Co-authored-by: Daira-Emma Hopwood <daira@jacaranda.org>

Author: M0nkeyFl0wer

src/projects/zcash/index.yaml

@@ -17,7 +17,7 @@ links:
   github: https://github.com/zcash/zcash/
   forum: https://forum.zcashcommunity.com/
   docs: https://zcash.readthedocs.io/en/latest/
-  whitepaper: https://zips.z.cash/protocol/protocol.pdf/
+  whitepaper: https://zips.z.cash/protocol/protocol.pdf
   block_explorer: https://3xpl.com/zcash
   governance: https://zips.z.cash
   twitter: https://twitter.com/zcash