Update agile index
Update agile testing guidance
Update retrospectives guide
Update quality guidance
Update what agile looks like
Revise features of agile guidance
Revise continuous delivery guidance
Minor whitespace changes to continuous delivery
Update writing user stories
Newline
clarify product manager
Clarify meaning of retrospective
Remove retrospectives from continuous delivery
Style changes
Updates to retrospectives based on @annashipman's comments
Added acceptance criteria in user stories

This should be a discussion in GDS before pull request is merged
Update following @annashipman comments
Fold in @heathd's comments
Editorial changes in response to comments

Minor style changes also made.
Minor change to acceptance criteria based on feedback