Describe new metrics provided by VNS3 integration, update pointers, modernize language, add example dashboard

[bob-smetana]

What does this PR do?

Brings the description of the VNS3 integration up to reflect current reality.

Motivation

A new version of the datadog-agent plugin for VNS3 has been released, adding new reported metrics and other functionality.

Review checklist

• PR has a meaningful title or PR has the no-changelog label attached
• Feature or bugfix has tests
• Git history is clean
• If PR impacts documentation, docs team has been notified or an issue has been opened on the documentation repo
• If this PR includes a log pipeline, please add a description describing the remappers and processors.

Additional Notes

n/a

[bob-smetana]

Third time's the charm!

[brett0000FF]

Thanks, looks good! I just left a small suggestion to make one of the links more descriptive.

[bob-smetana]

Actually I may have an issue with the dashboard.json in here.
Guess regular support will be the best resource for that?

[bob-smetana]

Support was very helpful as always - one of the widgets on that dashboard was somehow tainted. JSON file imports correctly after recreating that widget.
I am satisfied that this is ready for merge upon final approval.

[bob-smetana]

Not to nag, just making sure this hasn't dropped off the radar.
Still happy with latest commit, ready for a merge.

[brett0000FF]

@bob-smetana - Thanks for this and apologies for the delay! We still need a couple required approvals before merging. Let me ping them to make sure it's on their radar.

CC @DataDog/agent-integrations @DataDog/reporting-and-sharing

[bob-smetana]

Polite reminder that this is ready for merge

[brett0000FF]

@steveny91 - Could you please merge this one for @bob-smetana ? Docs team doesn't usually merge these. Thanks!