Config option to exclude files

[jms1voalte]

Is your feature request related to a problem? Please describe.

When macOS stores files on a non-Apple filesystem, it stores metadata for file xxx in a file called ._xxx. It also creates a file called ".DS_Store" in some directories, to hold metadata about the directory itself.

In this case, cheat -l xxx shows the ._xxx files in its output.

Describe the solution you'd like

Good: don't show files whose names start with ., or ._, or whatever makes sense.

Better: add a conf.yml option so the user can configure a list of filename patterns which should never be shown.