[feature request] Consider only one folder in a git repository (eg. "docs" folder, standard mkdocs structure)

[paolobasso99]

Hello,
I would love GitJournal to support setting a subfolder as the base directory, considering all the links relative to that folder and excluding files outsides that folder.

In my setup, I am using mkdocs and all my notes are in the "docs" subfolder (standard structure).
This is not compatible with gitjournal because I define all the links relatively to that subfolder, eg "docs/folder/note.md" becomes "folder/note.md". There are also other files in the repository but they should be excluded from gitjournal (it is not a problem if they are downloaded).