When I move mouse over a Ribbon item in my custom Outlook Addin, there is a tooltip which mentions the name of the Addin and a link "Tell me more". Upon pressing this, it directs me to MS Lynk web page. How can I customize this in order to be directed to an alternative link.
The Fluent UI doesn't provide anything for that. You can read more about the Fluent UI (aka Ribbon UI) in the following series of articles in MSDN: