Maturity levels: Change "Complete" to "Competitive"

Overview

In https://gitlab.slack.com/archives/C0NFPSFA8/p1563977843067600, a discussion resurfaced around the "Complete" maturity level. This came up in the past as being a suboptimal term since it implies that we've reached some kind of end state and we're not working on the category anymore. This isn't the case.

Proposal

Change the maturity level "Complete" to "Competitive".