Update release process doc to suggest using svn mv and clarify the process for docs updating

[jihoonson]

Description

Using the subversion mv has a couple of benefits.

• It is way faster than committing release artifacts to the release repo.
• We can save bandwidth of ASF infra.
• We can avoid a mistake that we accidentally commit different artifacts than those in the dev repo.

I also clarified the steps to update docs.

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This PR has:

• been self-reviewed.

[asdf2014]

👍