kubectl: Update triage/support label references to kind/support

The label triage/support has been reclassified as kind/support. The
kind/* family of labels makes more logical sense, as they describe the
"kind" of thing an issue or PR is.

For more information, see the announcement email:
https://groups.google.com/g/kubernetes-dev/c/YcaJpsjjLKw/m/i15cLLx5CAAJ

Author: mrbobbytables

staging/src/k8s.io/kubectl/.github/ISSUE_TEMPLATE/support.md

@@ -1,7 +1,7 @@
 ---
 name: Support Request
 about: Support request or question relating to kubectl
-labels: triage/support
+labels: kind/support
 
 ---