Added path_prefix and strip_path_prefix

lib/kamal/configuration/docs/proxy.yml

@@ -74,6 +74,17 @@ proxy:
   # How long to wait for requests to complete before timing out, defaults to 30 seconds:
   response_timeout: 10
 
+  # Path-based routing
+  #
+  # For applications that split their traffic to different services based on the request path, 
+  # you can use path-based routing to mount services under different path prefixes.
+  path_prefix: '/api'
+  # By default, the path prefix will be stripped from the request before it is forwarded upstream. 
+  # So in the example above, a request to /api/users/123 will be forwarded to web-1 as /users/123. 
+  # To instead forward the request with the original path (including the prefix), 
+  # specify --strip-path-prefix=false
+  strip_path_prefix: false
+
   # Healthcheck
   #
   # When deploying, the proxy will by default hit `/up` once every second until we hit