doc: Update comments for new chain settings (-signet and -chain=signet)

src/qt/bitcoin.cpp

@@ -533,7 +533,7 @@ int GuiMain(int argc, char* argv[])
     // - QSettings() will use the new application name after this, resulting in network-specific settings
     // - Needs to be done before createOptionsModel
 
-    // Check for -chain, -testnet or -regtest parameter (Params() calls are only valid after this clause)
+    // Check for chain settings (Params() calls are only valid after this clause)
     try {
         SelectParams(gArgs.GetChainName());
     } catch(std::exception &e) {