Link to Docker setup in gRPC example README.md
Link to Docker setup in gRPC example README.md

Add a link to instructions to set up the environment to the gRPC example
README.md.

Also remove `cd` instruction, since we have restructured our examples
workflow.

PiperOrigin-RevId: 206946894

google/asylo,google/asylo,google/asylo,google/asylo,google/asylo,google/asylo