clarify that users should not directly use the log bridge API (#5837)

Fixes #5681

Author: dashpole

log/doc.go

@@ -4,8 +4,10 @@
 /*
 Package log provides the OpenTelemetry Logs Bridge API.
 
-This package is intended to be a bridge between existing logging libraries and
-OpenTelemetry. It is not designed to be a logging API itself.
+This package is intended to be used by bridges between existing logging
+libraries and OpenTelemetry. Users should not directly use this package as a
+logging library. Instead, install one of the bridges listed in the
+[registry], and use the associated logging library.
 
 # API Implementations
 
@@ -68,5 +70,7 @@ It is strongly recommended that authors only embed
 go.opentelemetry.io/otel/log/noop if they choose this default behavior. That
 implementation is the only one OpenTelemetry authors can guarantee will fully
 implement all the API interfaces when a user updates their API.
+
+[registry]: https://opentelemetry.io/ecosystem/registry/?language=go&component=log-bridge
 */
 package log // import "go.opentelemetry.io/otel/log"