4.x: Add documentation for server.base-path (#9677)

* Add documentation for server.base-path

Author: barchetta

docs/src/main/asciidoc/mp/jaxrs/jaxrs-applications.adoc

@@ -23,7 +23,15 @@
 
 include::{rootdir}/includes/mp.adoc[]
 
-== Jakarta REST Applications
+== Content
+
+- <<Overview, Overview>>
+- <<Discovery of REST Beans, Discovery of REST Beans>>
+- <<Setting Application Path, Setting Application Path>>
+- <<Access to Application Instances, Access to Application Instances>>
+- <<Injection Managers in Helidon, Injection Managers in Helidon>>
+
+== Overview
 
 The Jakarta REST specification (formerly JAX-RS) defines the notion of an `Application`
 subclass whose methods return resource and provider classes, singletons and properties. This is the

docs/src/main/asciidoc/mp/server.adoc

@@ -1,6 +1,6 @@
 ///////////////////////////////////////////////////////////////////////////////
 
-    Copyright (c) 2022, 2024 Oracle and/or its affiliates.
+    Copyright (c) 2022, 2025 Oracle and/or its affiliates.
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -369,6 +369,22 @@ server:
 
 See xref:{rootdir}/config/io_helidon_webserver_staticcontent_StaticContentFeature.adoc[Static Content Feature Configuration Reference] for details. The only difference is that we set welcome file to `index.html` by default.
 
+=== Re-direct root using `server.base-path`
+
+To redirect requests for the root path (`/`) to another path you can use the `server.base-path` property:
+
+[source,yaml]
+----
+server:
+  base-path: /static/index.html
+----
+
+For any HTTP request for `/` this will return a 301 with the `Location:` header set to the value of `server.base-path`.
+This is often used with Static Content Support to serve a specific `index.html`  when `/` is requested.
+
+Note that this feature is not for setting a context root for applications. To configure alternate context roots see
+see xref:jaxrs/jaxrs-applications.adoc#_setting_application_path[Setting Application Path].
+
 === Example configuration of routing
 
 A full configuration example (YAML):