Add Lefthook.gitignore

[scop]

Reasons for making this change:

I'm a lefthook user. Lefthook supports local config overrides that should not be checked into git.

Links to documentation supporting these rule changes:

See links in the comments of the added gitignore.

If this is a new template:

• Link to application or project’s homepage: https://github.com/evilmartians/lefthook

[scop]

FYI @mrexox

[github-actions[bot]]

This PR is stale because there have been no updates in 90 days. It will close after 180 days of inactivity. Leave a comment if you want to keep it open :smile:

[scop]

Rebased, updated doc links, added some more to-be-ignored file patterns. Not stale!