Update website with LF trademark disclaimer

[doug-walker]

As recently discussed in the tech project leads Slack, ASWF websites should have an LF trademark disclaimer.

Copyright © PROJECTNAME a Series of LF Projects, LLC
For web site terms of use, trademark policy and other project policies please see https://lfprojects.org/.

The OCIO website should be updated accordingly, it currently says:
copyright © 2020 OpenColorIO Contributors

The trademarks are all owned by the LF, ASWF is not a separate legal entity.

Note that this has no bearing on the copyright in the code itself. (The website is a project-owned asset, while the contributors own the code itself.)

[ELVIS-KATO]

Hello, am interested in tackling this Issue, can it be assigned to me???

[doug-walker]

Thank you @ELVIS-KATO , I've assigned it to you!

[ELVIS-KATO]

Thanks @doug-walker, let me work on it real quick

[ELVIS-KATO]

I Made a PR, please take a look from here... @doug-walker

[doug-walker]

Closed as fixed via PR #2253 .