update the doc

## Reference Conformance Package Generation

<details>

<summary> <i> Expand for detailed procedure </i> </summary>

To generate reference conformance package for distribution

### Generate Reference Outputs and Readme.txt files

  ```shell

  sh scripts/ivas_conformance/ivas_be_conf_test_gen.sh

  ```

<details>

<summary> Example output of reference test generation </summary>

<pre><code>

::::::::::::::::::::::::

------------------------------------------

Generated html report: file:///home/dolby/git/ivas-codec/report_cmd.htm

------------------------------------------

=================================================

2571 passed, 538 skipped, 230 xfailed in 377.10s (0:06:17)

=================================================

Identified 5430 files from scripts

Removed 1515 files

Kept 5422 files

</code></pre>

</details>

### Generate Reference Decoded Outputs for the Reference Encoded files

  ```shell

  PYTHONPATH=scripts python scripts/ivas_conformance/runConformance.py --testvecDir $PWD/testvec --ref_build_path=testvec/bin  --regenerate-enc-refs

  ```

### Generate Reference MLD values

  ```shell

  PYTHONPATH=scripts python scripts/ivas_conformance/runConformance.py --testvecDir $PWD/testvec --ref_build_path=testvec/bin  --regenerate-mld-ref

  ```

### Generate a conformance package zip

  ```shell

  zip -r conformance.zip testvec scripts/ivas_conformance/runConformance.py  scripts/ivas_conformance/requirements.txt scripts/ivas_conformance/README.md scripts/ivas_conformance/thirdPartyLegalNotices.txt scripts/tools/Darwin/thirdPartyLegalnotices  scripts/tools/Darwin/LICENSE_wav-diff.txt scripts/tools/Darwin/wav-diff scripts/tools/Linux/thirdPartyLegalnotices  scripts/tools/Linux/LICENSE_wav-diff.txt scripts/tools/Linux/wav-diff scripts/tools/Win32/thirdPartyLegalnotices  scripts/tools/Win32/LICENSE_wav-diff.txt scripts/tools/Win32/wav-diff.exe

  ```

</details>