Improve oh-my-zsh installation instructions

[adamchainz]

• Tweak the wording to try use consistent terminology e.g. clone instead of copy, customization directory instead of “custom plugins” directory.
• Add code highlighting.
• plugins pre-exists for all oh-my-zsh users. Better to tell users to add to that line rather than add a new plugins=(... $plugins) line and how to place that.

[adamchainz]

Could not find a usable config.yml, you may have revoked the CircleCI OAuth app.

Please sign out of CircleCI and log back in with your VCS before triggering a new pipeline.

[MichaelAquilina]

Could not find a usable config.yml, you may have revoked the CircleCI OAuth app.

Please sign out of CircleCI and log back in with your VCS before triggering a new pipeline.

I think circleci revoked all GitHub SSH keys recently due to their incident so this is likely the issue. I'll fix it as soon as I'm at my laptop

[adamchainz]

Done.

FYI you could do that with gh pr checkout 122 to get my branch locally.

[adamchainz]

Now nothign is running...

[MichaelAquilina]

Looks like you have a minor linting issue in your README but should be good to go after :)

[adamchainz]

Woops, fixed

[MichaelAquilina]

How did the pipeline break again 😅

[MichaelAquilina]

The lint issue is fixed on master so merging as is to make this easier :)

[adamchainz]

Yay!