improve formatting

doc/README.md

@@ -3,7 +3,7 @@
 ## User documentation
 
 - [API](api/README.md) Automate GitLab via a simple and powerful API.
-- [CI](ci/README.md) GitLab Continuous Integration (CI) getting started, .gitlab-ci.yml options, and examples.
+- [CI](ci/README.md) GitLab Continuous Integration (CI) getting started, `.gitlab-ci.yml` options, and examples.
 - [GitLab as OAuth2 authentication service provider](integration/oauth_provider.md). It allows you to login to other applications from GitLab.
 - [GitLab Basics](gitlab-basics/README.md) Find step by step how to start working on your commandline and on GitLab.
 - [Importing to GitLab](workflow/importing/README.md).