WI #23 [BUG]: Helm chart reference is incorrect in readme.

[LavinMotwani]

Fixed the helm chart reference in readme

Please refer to our contributing docs for any questions on submitting a pull request.
Issues are required for both bug fixes and features.

Resolves #23

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Describe behaviour before the change

• Link to the notification charts from readme file was not working & giving "404 not found".

Describe behaviour after the change

• Link to the notification charts from readme file is woking & redirecting to helm charts notification-centre (api & sp).

Pull request checklist

• I have read the CONTRIBUTING.md
• My code follows the code style of this project
• Tests for the changes have been added (for bug fixes / features)
• All new and existing tests passed.
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

• Yes
• No

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