[ISSUE-216] Add CHANGELOG for v6.0.0

[jama5262]

What does this PR do?

Add CHANGELOG for v6.0.0

Issue Reference

Fixes #216

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Maintenance change (non-breaking change such as upgrading a dependency, refactoring, or making a lint fix)
• [x] Documentation update
• [ ] Breaking change (a fix or feature that would cause existing functionality to change)

Screenshots

If applicable, add screenshots to help explain your problem.

Checklist

• [ ] Wrote additional tests, if needed
• [ ] All tests have passed
• [ ] I have updated the documentation accordingly, if needed.

Additional Information

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (c907281) 96.30% compared to head (3fbfbb3) 96.30%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #217 +/- ## ======================================= Coverage 96.30% 96.30% ======================================= Files 34 34 Lines 1544 1544 ======================================= Hits 1487 1487 Misses 57 57 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jama+Mohamed). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jama+Mohamed)

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