Update release process about the credentials of spark-upload

PyPI requires a token to make a release now. This PR updates the release process.

Author: Hyukjin Kwon <gurwls223@apache.org>

Closes #504 from HyukjinKwon/minor-pypi-release-update.

release-process.md

@@ -232,7 +232,7 @@ and the same under [https://repository.apache.org/content/groups/maven-staging-g
 <h4>Upload to PyPI</h4>
 
 You'll need the credentials for the `spark-upload` account, which can be found in
-<a href="https://lists.apache.org/thread.html/2789e448cd8a95361a3164b48f3f8b73a6d9d82aeb228bae2bc4dc7f@%3Cprivate.spark.apache.org%3E">this message</a>
+<a href="https://lists.apache.org/thread.html/2789e448cd8a95361a3164b48f3f8b73a6d9d82aeb228bae2bc4dc7f@%3Cprivate.spark.apache.org%3E">this message</a> and <a href="https://lists.apache.org/thread/j4hq7v4c6bl8dx6n7q5pt7q1lcg3zwjc">this message</a>
 (only visible to PMC members).
 
 The artifacts can be uploaded using <a href="https://pypi.org/project/twine/">twine</a>. Just run:

site/release-process.html

@@ -372,7 +372,7 @@ <h4>Upload to Apache release directory</h4>
 <h4>Upload to PyPI</h4>
 
 <p>You&#8217;ll need the credentials for the <code class="language-plaintext highlighter-rouge">spark-upload</code> account, which can be found in
-<a href="https://lists.apache.org/thread.html/2789e448cd8a95361a3164b48f3f8b73a6d9d82aeb228bae2bc4dc7f@%3Cprivate.spark.apache.org%3E">this message</a>
+<a href="https://lists.apache.org/thread.html/2789e448cd8a95361a3164b48f3f8b73a6d9d82aeb228bae2bc4dc7f@%3Cprivate.spark.apache.org%3E">this message</a> and <a href="https://lists.apache.org/thread/j4hq7v4c6bl8dx6n7q5pt7q1lcg3zwjc">this message</a>
 (only visible to PMC members).</p>
 
 <p>The artifacts can be uploaded using <a href="https://pypi.org/project/twine/">twine</a>. Just run:</p>