hack/yaml-lint: No-op this script

Temporarily make the script a no-op while we work out whether we want
to keep this.  It's currently complaining about the YAML output from
Glide in the previous commit [1]:

  ./glide.yaml
    1:1       warning  missing document start "---"  (document-start)
    3:1       error    wrong indentation: expected 2 but found 0  (indentation)
    5:1       error    wrong indentation: expected 2 but found 0  (indentation)
    38:1      error    wrong indentation: expected 2 but found 0  (indentation)

Dropping the script entirely would break CI [2].  Alex is ok dropping
yamllint entirely, but I'm half-interested in keeping it around in
case we decide to move any static YAML assets
(e.g. pkg/asset/manifests/content/tectonic/rbac/role-user.go) over
into data/data.

[1]: https://storage.googleapis.com/origin-ci-test/pr-logs/pull/openshift_installer/370/pull-ci-openshift-installer-yaml-lint/636/build-log.txt
[2]: https://github.com/openshift/release/blob/d7ea5b36da63140fbb99c293aadde3bb279a24f9/ci-operator/jobs/openshift/installer/openshift-installer-master-presubmits.yaml#L354

Author: wking

CONTRIBUTING.md

@@ -42,7 +42,6 @@ For contributors who want to work up pull requests, the workflow is roughly:
     hack/shellcheck.sh
     hack/tf-fmt.sh -list -check
     hack/tf-lint.sh
-    hack/yaml-lint.sh
     ```
 7. Submit a pull request to the original repository.
 8. The [repo](OWNERS) [owners](OWNERS_ALIASES) will respond to your issue promptly, following [the ususal Prow workflow][prow-review].

hack/yaml-lint.sh

@@ -1,4 +1,5 @@
 #!/bin/sh
+exit 0  # temporarily disable while we work out whether to drop this
 if [ "$IS_CONTAINER" != "" ]; then
   yamllint --config-data "{extends: default, rules: {line-length: {level: warning, max: 120}}}" .
 else