Update IModel Documentation

[JKamsker]

Added documentation according to https://www.rabbitmq.com/queues.html

Proposed Changes

Just docs

Types of Changes

What types of changes does your code introduce to this project?
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• Documentation improvements (corrections, new content, etc)

Checklist

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the PR. If you're unsure about any of them, don't hesitate to ask on the
mailing list. We're here to help! This is simply a reminder of what we are
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• I have read the CONTRIBUTING.md document
• I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)
• All tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in related repositories

Further Comments

If this is a relatively large or complex change, kick off the discussion by
explaining why you chose the solution you did and what alternatives you
considered, etc.

[michaelklishin]

Thank you!

[sungam3r]

indentation