docs(rpc): deprecate platform user

Related to dashpay/dash#6209

docs/core/api/remote-procedure-calls.md

@@ -74,11 +74,9 @@ In this example, user1 can only call `getnetworkinfo`, user2 can only call `getn
 
 ### Restricted Access Users
 
-:::{note}
-This feature is only available on masternodes
-:::
+:::{deprecated} 22.0.0
 
-As of Dash Core 0.17.0, an option is provided to add an RPC user that is restricted to a small subset of RPCs that will be used by Dash Platform. The `platform-user` configuration value sets the name of the RPC user to be restricted.
+Since Dash Core 0.17.0, an option is provided to add an RPC user that is restricted to a small subset of RPCs used by Dash Platform. The `platform-user` configuration value sets the name of the RPC user to be restricted.
 
 The `platform-user` configuration value must be set to a previously configured [rpcauth user](#rpc-auth-security).
 
@@ -92,6 +90,8 @@ Only the following RPCs are accessible to the restricted user:
 * [`quorum verify`](../api/remote-procedure-calls-evo.md#quorum-verify)
 * [`verifyislock`](../api/remote-procedure-calls-evo.md#verifyislock)
 
+:::
+
 ### Default Connection Info
 
 The Dash Core RPC service listens for HTTP `POST` requests on port 9998 in [mainnet](../resources/glossary.md#mainnet) mode, 19998 in [testnet](../resources/glossary.md#testnet), or 19898 in [regression test mode](../resources/glossary.md#regression-test-mode). The port number can be changed by setting `rpcport` in `dash.conf`. By default the RPC service binds to your server's [localhost](https://en.wikipedia.org/wiki/Localhost) loopback network interface so it's not accessible from other servers. Authentication is implemented using [HTTP basic authentication](https://en.wikipedia.org/wiki/Basic_access_authentication). RPC HTTP requests must include a `Content-Type` header set to `text/plain` and a `Content-Length` header set to the size of the request body.