Navigation to Triggers resource panels

[ncskier]

This work is under epic #509

Expected Behavior

I expect there to be links in the left navigation menu that will take me to each Triggers resource page (TriggerTemplate, TriggerBinding, and EventListener).

Here is the latest wireframe from #509 for the navigation menu (EventListeners are selected in the example):

Actual Behavior

There are no menu items in the left navigation menu for the Triggers resource pages (TriggerTemplate, TriggerBinding, and EventListener).

Additional Info

• Tekton Triggers README: https://github.com/tektoncd/triggers

[mii-w]

I think it makes more sense to have Trigger Resources grouped together under the Tekton Resources category

[mii-w]

Because Triggers and Webhooks will work together - grouped together

[a-roberts]

We have this now 🎈 here's how it looks so far

For any changes e.g. groupings we can raise under a new issue, otherwise closing