Is your feature request related to a problem? Please describe

I already have a well formed .gitignore in my root directory.
Nevertheless, mani sync adds it's own stuff to the .gitgnore file.

Describe the solution you'd like

I would like to be able to switch off (by default) the changes to the .gitignore, e.g. by adding an entry to the configuration file like adjust_gitignore (setting it to false, having true as the default).