Update docs to reflect the need to run the cycle_server executable to start the server

[stylesm]

Relates to the QuickStart docs (https://docs.microsoft.com/en-gb/azure/cyclecloud/quickstart-install-cyclecloud)

In order to access the server in a web browser, you need to SSH into the VM and run the following:

sudo /opt/cycle_server/cycle_server

This is presumably for the good reason that because the first time you visit the server in a web browser it goes through a setup process, and you would want to restrict access to the server to certain IPs/etc to prevent somebody else finding the setup screen and screwing up your installation.