Add OAuth2 docs

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

admin_manual/configuration_server/index.rst

@@ -21,5 +21,6 @@ Server configuration
    automatic_configuration
    server_tuning
    theming
+   oauth2
 
 .. Intentional disabled antivirus_configuration

admin_manual/configuration_server/oauth2.rst

@@ -0,0 +1,36 @@
+======
+OAuth2
+======
+
+Nextcloud allows connecting external services (for example Moodle) to your Nextcloud.
+This is done via OAuth2. See `RFC6749 <https://tools.ietf.org/html/rfc6749>`_ for the
+OAuth2 specification.
+
+Note: Nextcloud only supports confidential clients.
+
+Add an OAuth2 Application
+-------------------------
+
+Head over to your Administrator Security Settings. Here you can add a new OAuth2 client.
+
+TODO: Figure
+
+Enter a name. And a redirection url.
+
+You should now have a Client Identifier and Secret. Enter those into your OAuth2 client.
+
+As well as:
+
+Authorization endpoint: SERVER/apps/oauth2/authorize
+Token endpoint: SERVER/apps/oauth2/api/v1/token
+
+
+The access token
+----------------
+
+The access token obtained is a so called Bearer token. Which means that for request to the
+Nextcloud server you will have to send the proper authorization header.
+
+Authorization: Bearer <TOKEN>
+
+Note that apache by default strips this. Make sure you have mod_rewrite and mod_env enabled.