* Add example configuration for Caddy v2

Add a basic example how to get synapse-admin running behind Caddy v2 proxy.

* Improve working, fix typos

* Fix typos

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

Related to https://github.com/Awesome-Technologies/synapse-admin/issues/132

Regression since 63a49bb2dc.

Related to #685 (Github Issue).

We now automatically expose the APIs when Synapse Admin is enabled.

Fixes #562 (Github Issue)