Directory checks & print statement updates

[klmcadams]

• Updated README.rst to provide more details about how to set up your repository with reuse and how to run the hook on directories other than src
• Removed linkcheck_ignore from conf.py since the repo is public
• Added default_dir variable to easily change the default directory the loc argument is given
• Added a check if the default_dir exists, and corresponding instructions if it doesn't exist
• Added tests to check the above changes

[RobPasMue]

I edited the README.rst file to render properly

And I also took advantage of the PR and added pre-commit.ci to it =)

Thanks for the PR @klmcadams!

[RobPasMue]

Let me work on the checks... I might do some changes

[RobPasMue]

LGTM! Merging!