Improvements to the front page for release (#121)

- Add a sentence about the relationship of OpenPBR to the ASWF.
- Remove a sentence about the confidentiality of the OpenPBR repository.
- Remove the phrase "work-in-progress" from the link to the reference implementation.
- Update the spelling of "über-surface" to match the specification.

README.md

@@ -4,14 +4,14 @@
     <img src="images/title.jpg" width="70%" title="OpenPBR logo (placeholder)"/>
 </p>
 
-A white paper specifying an über surface shader that aims to provide a material representation capable of accurately modeling the vast majority of materials used in practical visual effects and feature animation productions.
+A white paper specifying an über-surface shader that aims to provide a material representation capable of accurately modeling the vast majority of materials used in practical visual effects and feature animation productions.
 
-The contents of this repository are strictly confidential and should not be copied, distributed or reproduced in whole or in part, nor passed to any third party outside of the approved contributors.
+OpenPBR is an open standard hosted by the Academy Software Foundation (ASWF), and is organized as a subproject of MaterialX.
 
 ### Resources
 
 * **[White paper](https://academysoftwarefoundation.github.io/OpenPBR/)** – typeset in [Markdeep](https://casual-effects.com/markdeep/)
-* **[Reference implementation](reference/open_pbr_surface.mtlx)** – written in [MaterialX](https://materialx.org/), work in progress
+* **[Reference implementation](reference/open_pbr_surface.mtlx)** – written in [MaterialX](https://materialx.org/)
 
 ### Discussion
 * **[GitHub issues](https://github.com/AcademySoftwareFoundation/OpenPBR/issues)**