📖 Use RIP-7212 Link in p256

Signed-off-by: Pascal Marco Caversaccio <pascal.caversaccio@hotmail.ch>

src/snekmate/utils/p256.vy

@@ -7,8 +7,8 @@
 @notice These functions can be used to verify signatures based on the
         non-Ethereum-native NIST P-256 elliptic curve (also known as
         secp256r1; see https://neuromancer.sk/std/secg/secp256r1). For
-        more technical details, please refer to EIP-7212:
-        https://eips.ethereum.org/EIPS/eip-7212.
+        more technical details, please refer to RIP-7212:
+        https://github.com/ethereum/RIPs/blob/master/RIPS/rip-7212.md.
         The implementation is inspired by dcposch's and nalinbhardwaj's
         implementation here:
         https://github.com/daimo-eth/p256-verifier/blob/master/src/P256Verifier.sol.