Add mdl for backwards compatibility

The docs lint job uses a universal Docker image which uses the
gitlab-docs project. Since older GitLab versions also rely on it,
we need to have the mdl gem for backwards compatibility.

1 files changed, 2 insertions, 0 deletions

diff --git a/Gemfile b/Gemfile
index 62600891..bedb3294 100644
--- a/Gemfile
+++ b/Gemfile
@@ -28,4 +28,6 @@ group :test, :development do
   gem 'highline', '~> 2.0'
   gem 'rspec', '~> 3.5'
   gem 'pry-byebug', '~> 3.7', require: false
+  # Although we now use markdownlint-cli, we need the mdl gem for backwards compatibility
+  gem 'mdl'
 end