Feature/continous integration continous delivery

[Shiun]

Initial draft of the CI/CD guide. Any feedback greatly appreciated.

The guide starts with why CI/CD.

Then it goes into stages of CI and CD for PRs.

And a release to Prod process that follows gitflow using tags as triggers.

[tgaff]

It might also be worth reading through the existing https://guides.labzero.com/continuous_delivery/testing_strategy.html guide and trying to add some links to that or there's some very relevant sections in development workflow guide (testing) and going green

Trying to match tone slightly with them could be good too. I could see this being in a future PR too.