* feat(config): add `overrideDescription` option
Presets which extend many other presets used an `ignoreDeps: []` sentinel
to keep their own one-line summary in the onboarding PR instead of one line
per extended preset. Replace that hack with an explicit `overrideDescription`
option, which is consumed and removed while presets are resolved.
The resolved descriptions are unchanged. Repositories which set
`ignoreDeps: []` in their own config no longer lose all preset descriptions
in their onboarding PR.
* fixup! feat(config): add `overrideDescription` option
* fixup! feat(config): add `overrideDescription` option
* fixup! feat(config): add `overrideDescription` option