[doc] correct comment in chainparams

There are more than 3 networks.

src/chainparams.cpp

@@ -56,7 +56,7 @@ static CBlock CreateGenesisBlock(uint32_t nTime, uint32_t nNonce, uint32_t nBits
 }
 
 /**
- * Main network
+ * Main network on which people trade goods and services.
  */
 class CMainParams : public CChainParams {
 public:
@@ -173,7 +173,7 @@ public:
 };
 
 /**
- * Testnet (v3)
+ * Testnet (v3): public test network which is reset from time to time.
  */
 class CTestNetParams : public CChainParams {
 public:
@@ -266,7 +266,7 @@ public:
 };
 
 /**
- * Signet
+ * Signet: test network with an additional consensus parameter (see BIP325).
  */
 class SigNetParams : public CChainParams {
 public:
@@ -373,7 +373,8 @@ public:
 };
 
 /**
- * Regression test
+ * Regression test: intended for private networks only. Has minimal difficulty to ensure that
+ * blocks can be found instantly.
  */
 class CRegTestParams : public CChainParams {
 public:

src/chainparams.h

@@ -64,10 +64,7 @@ struct ChainTxData {
 
 /**
  * CChainParams defines various tweakable parameters of a given instance of the
- * Bitcoin system. There are three: the main network on which people trade goods
- * and services, the public test network which gets reset from time to time and
- * a regression test mode which is intended for private networks only. It has
- * minimal difficulty to ensure that blocks can be found instantly.
+ * Bitcoin system.
  */
 class CChainParams
 {