example_configs: add initial gogs.md documentation

Gogs is the origin for common git forges so we add a documentation which
may be beneficial for other use cases where lldap should be used with.
It appears to be in mantenance mode - the current example may have to be
extended in the future.

We adapt the official documentation example configuration to integrate
lldap with the more elaborated example.
The reader may also be interested in a more simple example at
[upstream](https://github.com/gogs/gogs/blob/main/conf/auth.d/ldap_simple_auth.conf.example).

example_configs/gogs.md

@@ -0,0 +1,46 @@
+# Gogs LDAP configuration
+
+Gogs can make use of LDAP and therefore lldap.
+
+The following configuration is adapted from the example configuration at [their repository](https://github.com/gogs/gogs/blob/main/conf/auth.d/ldap_bind_dn.conf.example).
+The example is a container configuration - the file should live within `conf/auth.d/some_name.conf`:
+
+```yaml
+$ cat /srv/git/gogs/conf/auth.d/ldap_bind_dn.conf
+id           = 101
+type         = ldap_bind_dn
+name         = LDAP BindDN
+is_activated = true
+is_default   = true
+
+[config]
+host               = ldap.example.com
+port               = 6360
+# 0 - Unencrypted, 1 - LDAPS, 2 - StartTLS
+security_protocol  = 1
+# You either need to install the LDAPS certificate into your trust store -
+# Or skip verification altogether - for a restricted container deployment a sane default.
+skip_verify        = true
+bind_dn            = uid=<binduser>,ou=people,dc=example,dc=com
+bind_password      = `yourPasswordInBackticks`
+user_base          = dc=example,dc=com
+attribute_username = uid
+attribute_name     = givenName
+attribute_surname  = sn
+attribute_mail     = mail
+attributes_in_bind = false
+# restricts on the `user_base`.
+filter             = (&(objectClass=person)(uid=%s))
+# The initial administrator has to enable admin privileges.
+# This is only possible for users who were logged in once.
+# This renders the following filter obsolete; Though its response is accepted by Gogs.
+admin_filter       = (memberOf=cn=<yourAdminGroup>,ou=groups,dc=example,dc=com)
+```
+
+The `binduser` shall be a member of `lldap_strict_readonly`.
+The group `yourAdminGroup` should be adapted to your requirement - Otherwise the entire line can be omitted.
+The diamond brackets are for readability and are not required.
+
+## Tested on Gogs
+
+v0.14+dev via podman 4.3.1