I added a check for case-sensitivity to the regex's. In my repositories, I have both a Docs and Demos folder and those wouldn't have been matched before. Now, they would.
Documentation is an important part of a software project but is not
generally thought of as part of the code for that project. Repository
language statistics are used to quantify the project's code, so it makes
sense to exclude documentation from those computations.
Documentation files are recognized similarly to vendored files.
lib/linguist/documentation.yml contains regular expressions to match
common names for documentation files. A new linguist-documentation Git
attribute can be used to override those conventions.
