Tidy the "IT Ops" page up a bit.
This updates several things on https://about.gitlab.com/handbook/business-ops/it-ops-team/, including:
- It moves the welcome and upper contact sections below the table of contents.
- It changes the welcome heading level.
- It updates a couple link URLs.
- It links to the #it-ops Slack channel.
- It makes several capitalization adjustments, including capitalizing brand names.
- It fixes some spelling errors.
- It fixes some punctuation issues.
- It changes the implied "People… Operations" to "the People Group".
cc @wzabaglio