docs: Add coverage cache to the development/pipelines page

Signed-off-by: Rémy Coutable <remy@rymai.me>

doc/development/pipelines.md

@@ -485,17 +485,19 @@ request, be sure to start the `dont-interrupt-me` job before pushing.
 
 1. All jobs must only pull caches by default.
 1. All jobs must be able to pass with an empty cache. In other words, caches are only there to speed up jobs.
-1. We currently have 6 different caches defined in
+1. We currently have several different caches defined in
    [`.gitlab/ci/global.gitlab-ci.yml`](https://gitlab.com/gitlab-org/gitlab/blob/master/.gitlab/ci/global.gitlab-ci.yml),
    with fixed keys:
    - `.rails-cache`.
    - `.static-analysis-cache`.
+   - `.coverage-cache`
    - `.qa-cache`
    - `.yarn-cache`.
    - `.assets-compile-cache` (the key includes `${NODE_ENV}` so it's actually two different caches).
 1. Only 6 specific jobs, running in 2-hourly scheduled pipelines, are pushing (i.e. updating) to the caches:
    - `update-rails-cache`, defined in [`.gitlab/ci/rails.gitlab-ci.yml`](https://gitlab.com/gitlab-org/gitlab/blob/master/.gitlab/ci/rails.gitlab-ci.yml).
    - `update-static-analysis-cache`, defined in [`.gitlab/ci/rails.gitlab-ci.yml`](https://gitlab.com/gitlab-org/gitlab/blob/master/.gitlab/ci/rails.gitlab-ci.yml).
+   - `update-coverage-cache`, defined in [`.gitlab/ci/rails.gitlab-ci.yml`](https://gitlab.com/gitlab-org/gitlab/blob/master/.gitlab/ci/rails.gitlab-ci.yml).
    - `update-qa-cache`, defined in [`.gitlab/ci/qa.gitlab-ci.yml`](https://gitlab.com/gitlab-org/gitlab/blob/master/.gitlab/ci/qa.gitlab-ci.yml).
    - `update-assets-compile-production-cache`, defined in [`.gitlab/ci/frontend.gitlab-ci.yml`](https://gitlab.com/gitlab-org/gitlab/blob/master/.gitlab/ci/frontend.gitlab-ci.yml).
    - `update-assets-compile-test-cache`, defined in [`.gitlab/ci/frontend.gitlab-ci.yml`](https://gitlab.com/gitlab-org/gitlab/blob/master/.gitlab/ci/frontend.gitlab-ci.yml).
@@ -519,7 +521,7 @@ variable:
 
 ```shell
 echo "Downloading archived master..."
-wget -O /tmp/gitlab.tar.gz https://storage.googleapis.com/gitlab-ci-git-repo-cache/project-278964/gitlab-master.tar.gz
+wget -O /tmp/gitlab.tar.gz https://storage.googleapis.com/gitlab-ci-git-repo-cache/project-278964/gitlab-master-shallow.tar.gz
 
 if [ ! -f /tmp/gitlab.tar.gz ]; then
     echo "Repository cache not available, cloning a new directory..."