chore(doc): add 2.0.0 changelog in the repo

[mittachaitu]

Signed-off-by: mittachaitu sai.chaithanya@mayadata.io

What this PR does / why we need it: This PR adds 2.0.0 changelog in the repo.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

Checklist:

• [ ] Fixes #
• [ ] Labelled this PR & related issue with documentation tag
• [ ] PR messages has document related information
• [ ] Labelled this PR & related issue with breaking-changes tag
• [ ] PR messages has breaking changes related information
• [ ] Labelled this PR & related issue with requires-upgrade tag
• [ ] PR messages has upgrade related information
• [ ] Commit has unit tests
• [ ] Commit has integration tests