Add conformance submission content to Readme

Topics:

- Point out .csv files, and note that `opencl_conformance_tests_full.csv` defines the full list of subtests required for conformance
- Document purpose of run_conformance.py; note that it's a utility, not a required script
- Point out submission template `submission_details_template.txt`
- Refer (link?) to [Conformance Process Document](https://www.khronos.org/files/conformance_procedures.pdf)

Start by locating the repository README and review the existing conformance-related sections. Add the requested references for the CSV files, run_conformance.py, submission_details_template.txt, and the Conformance Process Document, then verify that the filenames and link are accurate.

Written by the indexing model from the issue text.