3833 - adding containers link to agent section

[cswatt]

What does this PR do?

Just adds an extra link in the left nav to the containers section for extra discoverability

Motivation

Additional Notes

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Reviewer checklist

• [ ] Review the changed files.
• [ ] Review the URLs listed in the Preview section.
• [ ] Check images for PII
• [ ] Review any mentions of "Contact Datadog support" for internal support documentation.

[jtappa]

This duplication intermittently gives some weird results of the left nav bar snapping to not at all the right location for me, I think because it's trying to scroll to both locations of "Containers" in left nav at once and so it ends up somewhere in the middle. We might need websites' help on this? Unless we're ok with this behavior.

[cswatt]

i don't think this is a good idea anymore. closing