Add Slack Channel - vSphere CSI Driver assessment

Adding this slack channel for coordinating and performing the vSphere CSI Driver self asessment!

Author: aladewberry

communication/slack-config/sig-security/config.yaml

@@ -4,3 +4,4 @@ channels:
   - name: sig-security-docs
   - name: sig-security-tooling
   - name: sig-security-assessments
+  - name: sig-security-assess-vsphere-csi-driver