Add some docs on ldap development

docs/development/ldap/README.md

@@ -0,0 +1,31 @@
+---
+sidebar_navigation:
+  title: LDAP development setup
+  priority: 920
+---
+
+# Set up a development LDAP server
+
+**Note:** This guide is targeted only at development with OpenProject. For the LDAP configuration guide, please see this [here](../../system-admin-guide/authentication/ldap-authentication/)
+
+
+OpenProject comes with a built-in LDAP server for development purposes. This server uses [ladle gem](https://github.com/NUBIC/ladle)
+to run an underlying apacheDS server.
+
+This guide will show you how to set it up in your development instance.
+
+## Prerequisites
+
+- A local java/JRE environment installed (openjdk, java installed via homebrew, etc.)
+- A development setup of OpenProject (or any other configurable installation)
+
+## Running the LDAP server
+
+You only need to run this rake task to start the server:
+
+```bash
+./bin/rails ldap_groups:development:ldap_server
+```
+
+It will both output the different users and groups, as well as connection details. Starting this task will ensure
+an LDAP connection is created or updated to make sure you can use it right away.