This reverts merge request !19664

Update all references to version to include `v` for consistency.

Closes gitlab-org/gitlab-runner#2211

Closes #40164.

* Re-apply changes from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9666
* Update the wordings accordingly for the current revision
* Update the example to make it less confusing

- New cache page
- Move manual cache clearing to the new page
- Add all directives of cache in the yaml reference

Should fix https://gitlab.com/gitlab-org/gitlab-runner/issues/2652

[10.3] Fix path traversal in gitlab-ci.yml cache:key

See merge request gitlab/gitlabhq!2270

(cherry picked from commit c32d0c6807dfd41d7838a35742e6d0986871b389)

df29094a Fix path traversal in gitlab-ci.yml cache:key