* Fix: allow CORS requests to graphql API
In cluster setups the Graphql API endpoints are fetched as a CORS
request. We need to allow that.
* Fix: Allow CORS requests to ping endpoint
In cluster setups the ping is sent directly to the BBB server. So it
needs to allow CORS requests for cluster setups.
* Fix: construct relative API path for cluster setups
* Fix: adjust docs for cluster setup
As bbb-html5 client is static, setup instructions for cluster setup have
to be changed accordingly.
* Fix docs: remove superfluous ```yaml
This must have been introduced by accident.
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Co-authored-by: Daniel Schreiber <daniel.schreiber@hrz.tu-chemnitz.de>
