Add docs for scheduled pipeline variables

See https://gitlab.com/gitlab-org/gitlab-ce/issues/32568

doc/ci/variables/README.md

@@ -9,7 +9,7 @@ and a list of **user-defined variables**.
 The variables can be overwritten and they take precedence over each other in
 this order:
-1. [Trigger variables][triggers] or [scheduled pipeline variables](../../user/project/pipelines/schedules.md#making-use-of-scheduled-pipeline-variables) (take precedence over all)
+1. [Trigger variables][triggers] or [scheduled pipeline variables](../../user/project/pipelines/schedules#making-use-of-scheduled-pipeline-variables) (take precedence over all)
 1. [Secret variables](#secret-variables) or [protected secret variables](#protected-secret-variables)
 1. YAML-defined [job-level variables](../yaml/README.md#job-variables)
 1. YAML-defined [global variables](../yaml/README.md#variables)
@@ -37,7 +37,7 @@ future GitLab releases.**
 |-------------------------------- |--------|--------|-------------|
 | **CI**                          | all    | 0.4    | Mark that job is executed in CI environment |
 | **CI_COMMIT_REF_NAME**          | 9.0    | all    | The branch or tag name for which project is built |
-| **CI_COMMIT_REF_SLUG**          | 9.0    | all    | `$CI_COMMIT_REF_NAME` lowercased, shortened to 63 bytes, and with everything except `0-9` and `a-z` replaced with `-`. No leading / trailing `-`. Use in URLs, host names and domain names. |
+| **CI_COMMIT_REF_SLUG**          | 9.0    | all    | `$CI_COMMIT_REF_NAME` lowercased, shortened to 63 bytes, and with everything except `0-9` and `a-z` replaced with `-`. Use in URLs and domain names. |
 | **CI_COMMIT_SHA**               | 9.0    | all    | The commit revision for which project is built |
 | **CI_COMMIT_TAG**               | 9.0    | 0.5    | The commit tag name. Present only when building tags. |
 | **CI_DEBUG_TRACE**              | all    | 1.7    | Whether [debug tracing](#debug-tracing) is enabled |