Include openshift-4.12 schema (#200)

* Include openshift-4.12 schema.

This is coming from the most recent 4.12.z release (currently 4.12.87).

Generated using

  oc get --raw /openapi/v2 | jq --sort-keys 'del(.parameters, .paths[], .security, .securityDefinitions)' | sed -Ee 's/(Authorization: Bearer sha256)~[^ ]*/\1~REDACTED/;'

* Update README

---------

Co-authored-by: Moritz Clasmeier <mclasmeier@redhat.com>

Author: mclasmeier

internal/schemas/openapi-schemas/README.md

@@ -5,6 +5,8 @@
 - OpenShift 4.18 schema source:
   - Install openshift
   - `oc get --raw /openapi/v2 | jq --sort-keys 'del(.parameters, .paths[], .security, .securityDefinitions)'  > openshift-${version}.json`
+  - You might need to pipe the `oc` output through `sed -Ee 's/(Authorization: Bearer sha256)~[^ ]*/\1~REDACTED/;'` to satisfy
+    checks against credential leaking, because the in-line documentation might contain example tokens.
   - Update the `.info` in the resulting file
   - `gzip -9 openshift-${version}.json`