Merge pull request kubernetes#67201 from SneakyFish5/fix-link

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

fix OpenAPI link

**What this PR does / why we need it**:
Fix OpenAPI broken link

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```

Author: Kubernetes Submit Queue

api/openapi-spec/README.md

@@ -1,6 +1,6 @@
 # Kubernetes's OpenAPI Specification
 
-This folder contains an [OpenAPI specification][openapi] for Kubernetes API.
+This folder contains an [OpenAPI specification](https://github.com/OAI/OpenAPI-Specification) for Kubernetes API.
 
 ## Vendor Extensions