README doesn't explain how to run tests or how to validate the build

[yurivict]

Describe the bug

It should be explained in the README how to run tests and validate the build.

Are there test projects that one can build and see that everything works?

[bejado]

Our build.sh script takes a -u flag that builds and runs unit tests. For rendering validation, we typically run the gltf_viewer sample and check for visual regressions.