Create guide on deployment steps

[allishultes]

Is your feature request related to a problem? Please describe.

There is a lot to remember in terms of where and when and how to deploy changes, especially when we're working across Firebase functions and Storybook

Describe the solution you'd like

Updated documentation that covers the following scenarios:

• Steps to follow when updating Storybook and the Firebase app together
• Steps to follow when making changes to the Firebase repo / hosted client (i.e., remember to do both Jenkins and Travis, to test and to live...)
• Guidance on who in the team is responsible for pushing to prod/live, and when

Describe alternatives you've considered

Additional context

If we have any privacy concerns around this we should do this on Confluence. Tamsin's already created a helpful guide for releasing from the Storybook repo that should be referenced where appropriate: https://github.com/bbc/digital-paper-edit-storybook/wiki/Release-process-(draft)

[allishultes]

Draft: https://confluence.dev.bbc.co.uk/display/newslabs/Deployment