Rework Build and Deploy page to include `pre_start` command

[AnouckColson]

Where on docs.platform.sh should be changed?

https://docs.platform.sh/learn/overview/build-deploy.html

What exactly should be updated?

Further information on the pre_start command is needed (similar to the info provided on each hook in the table on https://docs.platform.sh/create-apps/hooks/hooks-comparison.html). There is confusion as to how it works and where it belongs in the whole build and deploy flow, so we need to make that clear.

Atm we only have mention of the pre_start command on https://docs.platform.sh/create-apps/hooks/hooks-comparison.html#deploy-hook with a link to the configuration side on https://docs.platform.sh/create-apps/app-reference/single-runtime-image.html#web-commands .

Additional context

See thread for screenshots with client questions/showing the confusion + newer request

No response

[chadwcarlson]

A typical example would be to regenerate / warm up cache

web:
    commands:
        pre_start: 'bash warmup-cache'

[fabpot]

A typical example would be to regenerate / warm up cache

web:
    commands:
        pre_start: 'bash warmup-cache'

Be careful here as the pre_start hook is not blocking, which means that the deploy hook can start running before the pre_start command is finished.