Merge branch 'update_renovate_docs_schedule' into 'main'

Adds docs for managing renovate schedule

See merge request gitlab-com/gl-infra/common-ci-tasks!870

renovate-bot.md

@@ -20,6 +20,18 @@ common_ci_tasks = {
 Note that if the `VAULT_SECRETS_PATH` configuration is present, this task will use Vault for resolution of `RENOVATE_GITLAB_TOKEN`. The token is restricted
 to only be accessible on the default protected branch.
+You can *optionally* set a schedule using cron format string eg.
+```terraform
+
+# Enable common-ci-task definitions
+common_ci_tasks = {
+    enabled      = true
+    renovate_bot = true
+    renovate_bot_schedule = "0 0 * * 2" # Every Tuesday at midnight UTC
+    ....
+}
+```
+
 ## Manual Setup
 For legacy project configurations, the following manual setup is required: