Added inf2 instance type

[jdwisman]

Description:

MANDATORY: PR needs test run output

Test Run Output: Please specify the release version, instance size and type, OS type and test output.

Training tutorial: Convergence graph for training tutorials Performance metrics average_throughput, latency_p50, latency_p99 and MFU% if available

Please make sure this PR contains correct classification terms (Alpha, Beta, and Stable).

If possible, provide your results or a link to them for the reviewer to check your work.

Issue #, sim, or t.corp if available:

Link to RTD for my changes: https://awsdocs-neuron-staging.readthedocs-hosted.com/en/YOUR_BRANCH_NAME/

Additional context:

PR Checklist

• [ ] I've completely filled out the form above!
• [ ] (If applicable) I've automated a test to safegaurd my changes from regression.
• [ ] (If applicable) I've posted test collateral to prove my change was effective and not harmful.
• [ ] (If applicable) I've added someone from QA to the list of reviewers. Do this if you didn't make an automated test or feel it's appropriate for another reason.
• [ ] (If applicable) I've reviewed the licenses of updated and new binaries and their dependencies to make sure all licenses are on the pre-approved Amazon license list. See https://inside.amazon.com/en/services/legal/us/OpenSource/Pages/BlessedOpenSourceLicenses.aspx.

Pytest Marker Checklist

(Coming soon...)

Reviewer Checklist

• For reviewer, before merging, please cross-check:
• [ ] I've verified the changes render correctly on RTD (link above)
• [ ] I've ensured the submitter completed the form
• [ ] (If appropriate) I've run tests to verify the contents of the change

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