Create Vale word substitution list

Problem to solve

As noted in #docs-team-onboarding chat, GitLab has some specific word usage requirements that the technical writing team can build tests for.

Further details

Proposal

Create a MVC of a generic word-substitution test for Vale, and include any other terms from https://about.gitlab.com/handbook/communication/#top-misused-terms that can be unambiguously tested for.

Who can address the issue

@aqualls

Other links/references

Part of the Vale implementation epic: &2497 (closed)