fix: update helm doc with NIM 2.18 and fix broken links

[balakoteswar]

Proposed changes

This PR contains helm deployment documentation support for older versions of NIM releases. Also fixed few broken links.

Problem: Currently there is no support for deploying the NIM using helm for NIM version v2.18.0 or lower

Solution: Updated the docs to support deploying the NIM using helm for NIM version v2.18.0 or lower

Testing: Performed local testing.

Closes # N/A

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[mjang]

Approving with @travisamartin 's suggestions