Fix redirect problem on dashboard + docs/tests on [web]

docs/configuration/backends/web.md

@@ -35,6 +35,15 @@ address = ":8080"
 # Default: false
 #
 readOnly = true
+
+ 
+# Set the root path for webui and API
+#
+# Deprecated
+# Optional
+#
+# path = "/mypath"
+#
 ```
 
 ## Web UI
@@ -375,3 +384,35 @@ curl -s "http://localhost:8080/api" | jq .
   }
 }
 ```
+
+## Path
+
+As web is deprecated, you can handle the `Path` option like this
+
+```toml
+[entrypoints.http]
+address=":80"
+
+[entrypoints.dashboard]
+address=":8080"
+
+[entrypoints.api]
+address=":8081"
+
+#Activate API and Dashboard
+[api]
+entrypoint="api"
+
+[file]
+  [backends]
+    [backends.backend1]
+      [backends.backend1.servers.server1]
+      url = "http://127.0.0.1:8081"
+
+  [frontends]
+    [frontends.frontend1]
+    entrypoints=["dashboard"]
+    backend = "backend1"
+      [frontends.frontend1.routes.test_1]
+      rule = "PathPrefixStrip:/yourprefix;PathPrefix:/yourprefix"
+```