update the usage steps in readme.md

# IVAS conformance scripts

This folder contains scripts for running IVAS conformance tests. This is a placeholder file for instructions.

no-BE conformance USAGE

Following CMDs needs to be executed from ivas-codec root folder:

################generate testvec package and encoder refs (temporary step to obtain testvec package, this step will be removed in final delivery)  ############

sh ivas_be_conf_test_gen.sh 

PYTHONPATH=scripts python scripts/ivas_conformance/runConformance.py --testvecDir $PWD/testvec --ref_build_path=testvec/ref_bin --cut_build_path=testvec/cut_bin --test-mode=ENC --regenerate-enc-refs

Encoder conformance:

	- PYTHONPATH=scripts python scripts/ivas_conformance/runConformance.py --testvecDir $PWD/testvec --ref_build_path=testvec/ref_bin --cut_build_path=testvec/cut_bin --test-mode=ENC

Decoder conformance:

	- PYTHONPATH=scripts python scripts/ivas_conformance/runConformance.py --testvecDir $PWD/testvec --ref_build_path=testvec/ref_bin --cut_build_path=testvec/cut_bin --test-mode=DEC

Renderer conformance:

	- PYTHONPATH=scripts python scripts/ivas_conformance/runConformance.py --testvecDir $PWD/testvec --ref_build_path=testvec/ref_bin --cut_build_path=testvec/cut_bin --test-mode=REND

Split renderer confomance:

	- <TBD>