Add a proper command list to Bedrock Dedicated Server how-to

The bundled "bedrock_server_how_to.html" file contains a list of server-specific commands like "save hold/resume/query" and "whitelist," but the full list of commands can only be found by using the "help" command on the command line. As there are 18 pages worth of commands, it would be helpful to add the full list of commands to the how-to or at least to a seperate document for people to access.

Example: https://pastebin.com/NCXw73dP