Add ISCC to multicodecs table (#252)

The ISCC is similarity preserving identifier for digital content. An ISCC is derived algorithmically from the digital content itself, just like cryptographic hashes. However, instead of using a single cryptographic hash function to identify data only, the ISCC uses a variety of algorithms to create a composite identifier that exhibits similarity-preserving properties (softhash). For an implementation of code `0xcc01` see: https://iscc-core.iscc.codes/#quick-start

Author: titusz

table.csv

@@ -475,6 +475,7 @@ skein1024-1016,                 multihash,      0xb3df,         draft,
 skein1024-1024,                 multihash,      0xb3e0,         draft,
 poseidon-bls12_381-a2-fc1,      multihash,      0xb401,         permanent, Poseidon using BLS12-381 and arity of 2 with Filecoin parameters
 poseidon-bls12_381-a2-fc1-sc,   multihash,      0xb402,         draft,     Poseidon using BLS12-381 and arity of 2 with Filecoin parameters - high-security variant
+iscc,                           softhash,       0xcc01,         draft,     ISCC (International Standard Content Code) - similarity preserving hash
 zeroxcert-imprint-256,          zeroxcert,      0xce11,         draft,     0xcert Asset Imprint (root hash)
 fil-commitment-unsealed,        filecoin,       0xf101,         permanent, Filecoin piece or sector data commitment merkle node/root (CommP & CommD)
 fil-commitment-sealed,          filecoin,       0xf102,         permanent, Filecoin sector data commitment merkle node/root - sealed and replicated (CommR)