[FEATURE] Document Installation for Triggers

[adambkaplan]

Is there an existing feature request for this?

• I have searched the existing feature requests

Is your feature request related to a problem or use-case? Please describe.

With shipwright-io/operator#240 complete, we need to update our install documentation to include Triggers.

Describe the solution that you would like.

Update the "Getting Started" and "Install" articles to include instructions on how to enable Triggers

Describe alternatives you have considered.

N/A

Anything else?

Merged PR: shipwright-io/operator#290