Merge branch 'cs-add-cii-badge' into 'master'

Add Core Infrastructure Initiative badge to README

Our Core Infrastructure Initiative Badge page: https://bestpractices.coreinfrastructure.org/projects/42

CII is a program by the Linux Foundation to track compliance with best practices in various large open source projects, we currently have a 100% passing rate for the badge.

We didn't list this before, even though we probably should. I asked Sid and he said there was no reason not to add it, so here we go :)

See merge request !6077

README.md

@@ -3,6 +3,7 @@
 [![build status](https://gitlab.com/gitlab-org/gitlab-ce/badges/master/build.svg)](https://gitlab.com/gitlab-org/gitlab-ce/commits/master)
 [![coverage report](https://gitlab.com/gitlab-org/gitlab-ce/badges/master/coverage.svg?job=coverage)](https://gitlab.com/gitlab-org/gitlab-ce/commits/master)
 [![Code Climate](https://codeclimate.com/github/gitlabhq/gitlabhq.svg)](https://codeclimate.com/github/gitlabhq/gitlabhq)
+![Core Infrastructure Initiative Best Practices](https://bestpractices.coreinfrastructure.org/projects/42/badge)](https://bestpractices.coreinfrastructure.org/projects/42)
 
 ## Canonical source