Added clarification for forked chains.

bip-MarcoPon-BlockchainURI.mediawiki

@@ -27,7 +27,7 @@ The URI follow this simple form:
 Where:
 
 ;chain:
-: (optional) to uniquely point to a specific chain, the hash of the corresponding genesis block is used (leading zeros included). In principle some kind of alias/mnemonic could also be used, but that is out of the scope of this BIP, and maybe could be developed in another subsequent one. If omitted (which would be the usual case), Bitcoin's mainnet is assumed. As a reference, see for example this code fragment from Bitcoin chainparams.cpp source:
+: (optional) to uniquely point to a specific chain, the hash of the corresponding genesis block is used (leading zeros included). For forked chains, the hash of the relevant first block after fork is used. In principle some kind of alias/mnemonic could also be used, but that is out of the scope of this BIP, and maybe could be developed in another subsequent one. If omitted (which would be the usual case), Bitcoin's mainnet is assumed. As a reference, see for example this code fragment from Bitcoin chainparams.cpp source:
   const std::map<std::string, uint256> CChainParams::supportedChains =
       boost::assign::map_list_of
       ( "main", uint256S("0x000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f"))