Document BUILD_FLAGS in the docs

[karpikpl]

Document BUILD_FLAGS in the docs

[simonjj]

@karpikpl The URL results in a 404 for me. Not sure why, also this file from the name seems to be a App Specific file which is used to configure Oryx but ultimately runs under Kudu.

[karpikpl]

I'm not sure what happened to that branch/commit.

I see BUILD_FLAGS referenced here: https://github.com/Azure-App-Service/KuduLite/blob/3854066bb50c3a1933aebbc4143c06c47535be68/Kudu.Core/Deployment/Oryx/OryxArguments.cs#L28

I think there are following values possible:

        Off,
        None,
        CompressModules,
        UseExpressBuild,
        UseTempDirectory,
        DeploymentV2

but last time I searched it was hard to find any documentation for them