docs(config options): rewrite ignoreScripts

[HonkingGoose]

Changes

• Drop Applicable for npm, bun, Composer and Copier only for now. as the auto-generated table has a list of supportedManagers.
• Drop Set this to true if running scripts causes problems., and instead explain Renovate's script allow/block behavior. Then users can choose what's best for their situation.
• Explain the default behavior (do not run scripts), and cover ways to run scripts:
  • Self-host Renovate
  • Pay for "Renovate Enterprise Cloud"
• Explain how to allow scripts when self-hosting Renovate

Context

@rarkins said:

Scripts can now be enabled for paying customers on Mend.io hosted apps, please get in touch with Mend.io sales about "Renovate Enterprise Cloud" if interested. We don't plan to allow script execution for free users as the risk is too high

• Why could renovate start drop pnpmfileChecksum from the lockfile? #30812 (reply in thread)

I'm adding the info above to the docs. Plus a general rewrite.

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[HonkingGoose]

Can you configure Renovate like this?

1. Allow script execution, by setting the self-hosted config option allowScripts=true.
2. But limit the risk, by only allowing the npm package manager to run scripts.

[rarkins]

Actually, allowScripts is a top-level global setting so is turned on for all managers or none

[HonkingGoose]

I dropped the section about the example config to allow scripts for just npm.

[HonkingGoose]

I think we have two things remaining:

• find way to use headings, without ignoring a markdownlint rule
• get another review from the maintainers

@viceice do you know how/if I can use headings properly?