Add documentation to maintain historical version config mappings

[ayildirim21]

Summary

As per https://github.com/numaproj/numaflow/pull/1683#discussion_r1569625987. We should also in the same file mention that version_mapping.go should be updated after each new release.

Use Cases

After a release, in case developer did not know which files to update.

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[KeranYang]

We should also in the same file mention that version_mapping.go should be updated after each new release.

I think it would be better that mention it in the releasing.md file.