[Don't merge yet] Add release dates in release notes

Looks like this:

Fixes #963

/cc @varshavaradarajan

Dates from: https://github.com/gocd/gocd/releases

@varshavaradarajan said it should be done on the downloads page too. Using the date from releases.json. That makes sense. Will do that tomorrow. Don't merge.

Ping! pls see if this is still relevant.

@kritika-singh3 - I think this can be closed. We added the release date to the downloads page.

@varshavaradarajan I think the PR was to add the release dates on the release notes. Is it not required anymore?

Nope. The downloads page makes a call and retrieves the releases.json. Which has the release date, so there is no manual step required. Here, when one edits the release notes, they need to remember and put that in. So, it's overkill. When the release date is already available on the downloads page.

I don't think @arvindsv will do that anymore. :P

@varshavaradarajan hmm. Agree with your logic. I'll leave the decision to @arvindsv :)