Merge #14741: doc: Indicate -rpcauth option password hashing alg

dcb70b1 Indicate -rpcauth option password hashing alg (Carl Dong)

Pull request description:

  By indicating the password hashing algorithm, users of bitcoin distributions without the script in `share/rpcauth` and users who don't want to rely on said script can use alternative means to generate the password hash.

  Question for reviewers: perhaps we should also indicate that it is specifically a HMAC-SHA-256 of the _**UTF-8**_ encoding of their password?

Tree-SHA512: 86b546c2e78699fa253da0c1e76b21ef60e9b6a5778826ac5136e764d70e3213044cc05cdb4786ba27968781647c46e358a823bbc2db7d45d041d291ee03b83c

Author: laanwj

src/init.cpp

@@ -500,7 +500,7 @@ void SetupServerArgs()
 
     gArgs.AddArg("-rest", strprintf("Accept public REST requests (default: %u)", DEFAULT_REST_ENABLE), false, OptionsCategory::RPC);
     gArgs.AddArg("-rpcallowip=<ip>", "Allow JSON-RPC connections from specified source. Valid for <ip> are a single IP (e.g. 1.2.3.4), a network/netmask (e.g. 1.2.3.4/255.255.255.0) or a network/CIDR (e.g. 1.2.3.4/24). This option can be specified multiple times", false, OptionsCategory::RPC);
-    gArgs.AddArg("-rpcauth=<userpw>", "Username and hashed password for JSON-RPC connections. The field <userpw> comes in the format: <USERNAME>:<SALT>$<HASH>. A canonical python script is included in share/rpcauth. The client then connects normally using the rpcuser=<USERNAME>/rpcpassword=<PASSWORD> pair of arguments. This option can be specified multiple times", false, OptionsCategory::RPC);
+    gArgs.AddArg("-rpcauth=<userpw>", "Username and HMAC-SHA-256 hashed password for JSON-RPC connections. The field <userpw> comes in the format: <USERNAME>:<SALT>$<HASH>. A canonical python script is included in share/rpcauth. The client then connects normally using the rpcuser=<USERNAME>/rpcpassword=<PASSWORD> pair of arguments. This option can be specified multiple times", false, OptionsCategory::RPC);
     gArgs.AddArg("-rpcbind=<addr>[:port]", "Bind to given address to listen for JSON-RPC connections. Do not expose the RPC server to untrusted networks such as the public internet! This option is ignored unless -rpcallowip is also passed. Port is optional and overrides -rpcport. Use [host]:port notation for IPv6. This option can be specified multiple times (default: 127.0.0.1 and ::1 i.e., localhost)", false, OptionsCategory::RPC);
     gArgs.AddArg("-rpccookiefile=<loc>", "Location of the auth cookie. Relative paths will be prefixed by a net-specific datadir location. (default: data dir)", false, OptionsCategory::RPC);
     gArgs.AddArg("-rpcpassword=<pw>", "Password for JSON-RPC connections", false, OptionsCategory::RPC);