New O/S support policy + enterprise support

[DRC]

Please take a moment to review our new operating system support policy:

https://virtualgl.org/Documentation/OSSupport
https://turbovnc.org/Documentation/OSSupport

To summarize, starting with VirtualGL and TurboVNC 3.0:
- We will only officially support current releases of RHEL/x86-64 (and
its work-alikes), Ubuntu LTS/amd64, macOS, and Windows ("current" = not
in an extended life-cycle phase) for free
- Support for other enterprise operating systems, or any operating
system in an extended life-cycle phase, will be provided only under a
paid support contract
- Support for other open source publicly-updated operating systems will
be provided by the community or under a paid support contract

Contact me for a support estimate. Also note that I provide other types
of enterprise support for VirtualGL and TurboVNC, including:

- Maintaining custom stable/bug-fix branches and CI builds of VirtualGL
and TurboVNC based around a specific release (including back-porting bug
fixes from newer releases.) Historically, I maintained these branches
for free, but going forward, they will be maintained only under a paid
support contract.
- Additional testing and support of GPUs other than those made by nVidia
and AMD