Review the installation/configuration.php-dist

See: https://github.com/joomla/joomla-cms/issues/4498

This is a review of the installation/configuration.php-dist file. I have add some comments move the default dbtype to mysqli and outcommend the root_user (<-- or is this realy needed?)

I don't know if this need any testing but it can be tested is the following:

1. download a clean staging
2. extract
3. move this file to the joomla root
4. change the needed settings
5. install the database manualy
6. make sure all works as if you use the installer.

Thanks @robations for pointing it out.
Suggest to remove that line because it isn't valid anymore. The number 42 used to be the id of the Super user. Not anymore, now it is a random number. Besides that, this line shouldn't be in here, because you only use it for emergency cases where you screwed the permissions and locked yourself out of the Super role.