docs(dev): add developer documentation about ldap

This explains how a developer is able to get a ldap server up and running and configure HedgeDoc to use it quickly.

Signed-off-by: Philip Molares <philip.molares@udo.edu>

docs/content/dev/auth/ldap.md

@@ -0,0 +1,34 @@
+# LDAP
+
+LDAP authentication can be tested with the [`test-openldap`](https://github.com/rroemhild/docker-test-openldap) docker image from [rroemhild](https://github.com/rroemhild).
+
+Simply run
+
+```sh
+docker run --rm -p 10389:10389 -p 10636:10636 rroemhild/test-openldap
+```
+
+and add the following to the `.env` file before starting the backend.
+
+```
+HD_AUTH_LDAPS="FUTURAMA"
+HD_AUTH_LDAP_FUTURAMA_PROVIDER_NAME="Futurama LDAP"
+HD_AUTH_LDAP_FUTURAMA_URL="ldap://localhost:10389"
+HD_AUTH_LDAP_FUTURAMA_SEARCH_BASE="ou=people,dc=planetexpress,dc=com"
+HD_AUTH_LDAP_FUTURAMA_SEARCH_FILTER=(&(uid={{username}})(objectClass=inetOrgPerson))
+HD_AUTH_LDAP_FUTURAMA_USERNAME_FIELD="uid"
+HD_AUTH_LDAP_FUTURAMA_USERID_FIELD="uid"
+HD_AUTH_LDAP_FUTURAMA_BIND_DN="cn=admin,dc=planetexpress,dc=com"
+HD_AUTH_LDAP_FUTURAMA_BIND_CREDENTIALS="GoodNewsEveryone"
+```
+
+You should then be able to log in with either of these logins (`username` : `password`):
+
+- `professor` : `professor`
+- `fry` : `fry`
+- `zoidberg` : `zoidberg`
+- `hermes` : `hermes`
+- `leela` : `leela`
+- `bender` : `bender`
+- `amy` : `amy`
+