docs: specify address for worker listener configuration (#749)

Co-authored-by: Jeff Mitchell <jeffrey.mitchell@gmail.com>

website/content/docs/configuration/worker.mdx

@@ -14,6 +14,7 @@ The `worker` stanza configures Boundary worker-specific parameters.
 worker {
   name = "example-worker"
   description = "An example worker"
+  address = 127.0.0.1
   public_addr = "5.1.23.198"
 }
 ```
@@ -23,6 +24,9 @@ cluster.
 
 - `description` - Specifies a friendly description of this worker.
 
+- `address` - Specifies the IP address for the worker listener to bind on. Defaults to
+127.0.0.1:9202 if not specified. If address is specified but only an IP address is given, the port will default to 9202.
+
 - `public_addr` - Specifies the public host or IP address (and optionally port)
 at which the worker can be reached _by clients for proxying_. This defaults to
 the address of the listener marked for `proxy` purpose. This is especially
@@ -76,6 +80,7 @@ worker {
   # Name attr must be unique across workers
   name = "demo-worker-1"
   description = "A default worker created demonstration"
+  address = 127.0.0.1
 
   # Workers must be able to reach controllers on :9202
   controllers = [