Azure Correct and update Online Documentation

[bignay2000]

Description

1. https://www.flatcar.org/docs/latest/installing/cloud/azure/ is out of date.
2. custom data reference is out of date with the latest Azure CLI - $() syntax does not work, just use the filename directly
3. References Butane version 1.0.0 - please confirm examples work with the newer Butane 1.1.0
4. Update the references to the lastest stable version 3602.2.1
5. Mention the "latest" tag
6. Add a note about the differences between a Gen1 image and Gen2 image (kinvolk:flatcar-container-linux:stable-gen2:latest)
7. Add a note that TrustedLaunch is not supported with Gen2 image
8. Add a note that encrypted boot is not supported with Gen2 image
9. The json file needs to be a single line - (do not use --pretty butane flag) - this seems to work fine in non-Azure flatcar.

az vm create --name node-1 --resource-group group-1 --admin-username core --custom-data "$(cat config.ign)" --image kinvolk:flatcar-container-linux:stable:2345.3.0
This "$()" syntax no longer works, new az cli will load the file.
az vm create --name node-1 --resource-group group-1 --admin-username core --custom-data config.ign --image kinvolk:flatcar-container-linux:stable:3602.2.1

az vm create --name node-1 --resource-group group-1 --admin-username core --custom-data config.ign --image kinvolk:flatcar-container-linux:stable-gen2:latest

I think Flatcar Pro is no longer a thing, so page needs that removed.

Update to use Ignition 1.1.

Impact

Ability to cross train my team and show off how amazing Flatcar Linux on Azure

Additional Information

#501
#1218
#1249
#1253

[bignay2000]

@sayanchowdhury working through migrating my flatcar configuration from VMWare ESXi to Azure.