Related to:
- https://github.com/etkecc/synapse-admin/pull/126
- https://github.com/etkecc/synapse-admin/releases/tag/v0.10.3-etke27

People who wish to disable this and keep their `/.well-known/matrix/client` file tidier
can do it via:

```yml
matrix_static_files_file_matrix_client_property_cc_etke_synapse_admin_enabled: false
```