Doc updates for NLB instance mode support

[kishorj]

Update documentation for the NLB instance mode support in v2.2.0 release.

[codecov-commenter]

Codecov Report

Merging #2007 (2c4f702) into main (edaddf5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #2007   +/-   ##
=======================================
  Coverage   49.24%   49.24%           
=======================================
  Files         130      130           
  Lines        7034     7034           
=======================================
  Hits         3464     3464           
  Misses       3292     3292           
  Partials      278      278           

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[k8s-ci-robot]

@kishorj: The following test failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-aws-load-balancer-controller-e2e-test	2c4f702	link	/test pull-aws-load-balancer-controller-e2e-test

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[kishorj]

/retest

[M00nF1sh]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kishorj, M00nF1sh

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