Creates a major release and updates the README

[cameronviner]

What does this PR do? (please provide any background)

Bumps the version number to 2.0 after my last PR introduced breaking change. I have also updated the README to detail the new deployment process.

What tests does this PR have?

None

How can this be tested?

Take a look at the README and make sure it makes sense

Screenshots / Screencast

What gif best describes how you feel about this work?

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• [x] I have checked our general contributing document and the project specific contributing document (if present) and I'm happy for this to be reviewed.

  Reviewers

Review 1

• [x] :+1:

By adding a +1 you are confirming you have...

• Witnessed the work behaving as expected (this could be on the author's machine or screencast).
• Checked for coding anti-patterns.
• Checked for appropriate test coverage.
• Checked all the tests are passing.

[ghost]

@cameronviner, thanks for your PR! By analyzing the blame information on this pull request, we identified @robhuzzey, @jackdcrawford and @jodiedoubleday to be potential reviewers

[jodiedoubleday]

Looks pretty straightforward to me. :shipit: