qemu-doc: provide details of supported build platforms

Describe the policy the project uses to decide which OS are supported as
build platforms. This will:

  - Allow maintainers to determine when the minimum version of a 3rd
    party piece of software can be increased without negatively
    impacting supported platforms.

  - Allow tailoring of CI environments to match the intended supported
    build platforms.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20180504160026.14017-2-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
1 file changed