Since this is a second round review, I'm going to trim more heavily.

> +# Git Hook scripts
> +
> +Gitano administrators may create, or delegate creation of

Perhaps worth a comma at the end of this line?

> +[Lua][lua] scripts to take action or provide further authentication
> +when content is pushed to a repository.

> +5.  The `refname`, `oldsha` and `newsha` as the third to fifth parameters

...second to fourth...

> +6.  For pre-receive or post-receive per-repository hooks as the third parameter,

...second...

> +7.  Global hooks work the same as per-repository hooks,
> +    except their first parameter is instead a callable function
> +    which will run the per-repository hook when called,
> +    so global hooks may either replace or augment per-repository hooks.

...except they are passed a callable function first, followed by the positional
parameters as described above.  The callable will run the per-repository
hook when called, ...

Otherwise I think it looks good.

If you're ok with the above changes, and don't think I've missed anything,
then I'm happy to apply these as part of a merge.