[extension/bearerauth] [docs ] Update settings documentation (#16171)

Update the readme to remove references to deprecated struct GRPCClientAuthenticator and provide correct usage of configuration

extension/bearertokenauthextension/README.md

@@ -6,26 +6,19 @@
 | Distributions | [contrib] |
 
 
-This extension implements `configauth.GRPCClientAuthenticator` and is to be used in gRPC receivers inside the `auth` settings as a means
-to embed a static token for every RPC call that will be made.
+This extension implements `configauth.ClientAuthenticator` and can be used in both http and gRPC receivers inside the `auth` settings, as a means to embed a static token for every RPC call that will be made.
 
 The authenticator type has to be set to `bearertokenauth`.
 
 ## Configuration
 
-One of the following two options is required. If a token **and** a tokenfile are specified, the token is **ignored**:
-
-- `scheme`: Specifies the auth scheme name. Defaults to "Bearer".
+- `scheme`: Specifies the auth scheme name. Defaults to "Bearer". Optional.
 
 - `token`: Static authorization token that needs to be sent on every gRPC client call as metadata.
- This token is prepended by `${scheme}` before being sent as a value of "authorization" key in
- RPC metadata.
 
-- `filename`: Name of file that contains a authorization token that needs to be sent on every
- gRPC client call as metadata.
- This token is prepended by `${scheme}` before being sent as a value of "authorization" key in
- RPC metadata.
+- `filename`: Name of file that contains a authorization token that needs to be sent in every client call.
 
+Either one of `token` or `filename` field is required. If both are specified, then the `token` field value is **ignored**. In any case, the value of the token will be prepended by `${scheme}` before being sent as a value of "authorization" key in the request header in case of HTTP and metadata in case of gRPC.
 
 **Note**: bearertokenauth requires transport layer security enabled on the exporter.
 
@@ -57,7 +50,7 @@ exporters:
  otlphttp/withauth:
  endpoint: http:https://localhost:9000
  auth:
- authenticator: bearertokenauth
+ authenticator: bearertokenauth/withscheme
 
 service:
  extensions: [bearertokenauth, bearertokenauth/withscheme]