Streamline routing

- put openapi doc behind `api/doc` instead of `app/doc`
- don't require `index.html` for the webapp

modules/microsite/docs/doc/install.md

@@ -150,8 +150,8 @@ $ ./docspell-joex*/bin/docspell-joex /path/to/joex-config.conf
 ```
 
 After starting the rest server, you can reach the web application at
-path `/app/index.html`, so using default values it would be
-`http://localhost:7880/app/index.html`.
+path `/app`, so using default values it would be
+`http://localhost:7880/app`.
 
 You should be able to create a new account and sign in. Check the
 [configuration page](configure.html) to further customize docspell.

modules/microsite/docs/doc/uploading.md

@@ -53,7 +53,7 @@ Example screenshot:
 
 This example shows a source with name "test". It defines two urls:
 
-- `/app/index.html#/upload/<id>`
+- `/app#/upload/<id>`
 - `/api/v1/open/upload/item/<id>`
 
 The first points to a web page where everyone could upload files into