chore(cli): Update keys add help message (#10730)

the command `gaiad keys add myKey --help` is printed as

```
      --account uint32           Account number for HD derivation
      --index uint32             Address index number for HD derivation
```
and it's not obvious that uint32 cannot accept its max value.
https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#extended-keys

Please close this if it is not required, request changes if there is better way to do this.

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client/keys/add.go

@@ -74,8 +74,8 @@ Example:
 	f.Bool(flags.FlagDryRun, false, "Perform action, but don't add key to local keystore")
 	f.String(flagHDPath, "", "Manual HD Path derivation (overrides BIP44 config)")
 	f.Uint32(flagCoinType, sdk.GetConfig().GetCoinType(), "coin type number for HD derivation")
-	f.Uint32(flagAccount, 0, "Account number for HD derivation")
-	f.Uint32(flagIndex, 0, "Address index number for HD derivation")
+	f.Uint32(flagAccount, 0, "Account number for HD derivation (less than equal 2147483647)")
+	f.Uint32(flagIndex, 0, "Address index number for HD derivation (less than equal 2147483647)")
 	f.String(flags.FlagKeyAlgorithm, string(hd.Secp256k1Type), "Key signing algorithm to generate keys for")
 
 	return cmd