Add Implementations section

[nurusanwe]

Adds a new Implementations section to the README, between the existing Specification and Resources sections.

This provides a dedicated place to reference open-source BSDF implementations of OpenPBR by the community and industry.

The first entry is Adobe OpenPBR BSDF, Adobe's open-source BSDF implementation of OpenPBR. The repository is currently being set up and will be populated during March 2026.

[jstone-lucasfilm]

@nurusanwe Since our existing Resources section already contains a list of OpenPBR implementations, perhaps we can just add this new one to the end of the list?

[linux-foundation-easycla]

• ✅ login: BrianSharpe / name: Brian Sharpe (08031ea)
• ✅ login: jstone-lucasfilm / name: Jonathan Stone (1a8a9aa, 4b602eb)
• ✅ login: msuzuki-nvidia / name: Masuo Suzuki (d317a56)
• ✅ login: portsmouth / name: Jamie (0262ba0, 120e3b5, 1a53140, 297d447, 34b2b22, 3845bc1, 3a388ef, 6213883, 7112029, 878a7e6, 87e3ecb, 8bf8248, ac355b7, ae29610, b3e14b6, e3194ef, fb1ac8e)
• ❌ The email address for the commit (864f907) is not linked to the GitHub account, preventing the EasyCLA check. Consult this Help Article and GitHub Help to resolve. (To view the commit's email address, add .patch at the end of this PR page's URL.) For further assistance with EasyCLA, please submit a support request ticket.

[nurusanwe]

Whatever is prefered is fine to me

It was mentioned during the OpenPBR meeting to have a new 'Implementation' section to have a dedicated category for this specific kind of contribution/resource

It could make sense if eventually we have more and more resources to add in the Readme but for now I agree it is not really needed

[nurusanwe]

Also I notice the commits I created with this PR are quite messy (sorry, been a long time not interacting on a public github project): I started from 1.2 branch and made PR on main ...

Well when we agree if we prefer adding a line in resources or adding a new Implementation section, I'll recreate a cleaner PR

Guess the best for this kind of improvement is a PR directly from main ? To just enrich the readme file , not relateed to 1.2 release
What do you think ?

[jstone-lucasfilm]

@nurusanwe I like your suggestion to start a new, cleaner PR, and the approach I use is to create a branch based on dev_1.2 in my fork, and then propose it as a PR to the dev_1.2 branch of the OpenPBR repository.