Need to add NGF team to CODEOWNERS for content in this directory

[mjang]

          ngf team wasn't added as reviewers to this for some reason

Originally posted by @sjberman in #155 (comment)

[mjang]

@ADubhlaoich I thought you fixed this with commit 15d93bd on Jan 28. Not sure what's happening

[ADubhlaoich]

I'm closing this: it works as intended. I have a suspicion about what might have gone wrong, and once I have confirmed this with future PRs it'll be something that'll have to be given to DocOps engineering.

Branches off the repository seem to automatically tag: my suspicion is branches off a fork behave differently.