Add rmqtt to Message Queue Section and Sort Alphabetically

[darixsamani]

This PR adds the rmqtt project to the Message Queue section and updates the list to ensure all entries(message queue) are sorted alphabetically according to the contribution guidelines.

[palfrey]

As per our CONTRIBUTING.md, entries should be sorted in alphabetical order, but this one isn't. Please see the build logs for details of where the entry should be. Note, if you have a username/repo-name project name listed, we use the entire thing, not just the repo-name, as we don't specially support those and always use the entire project name.

[darixsamani]

Hey @palfrey check it again please