GitHub: Fix exec in issue template. (kubernetes#12386)

Author: daviderli614

.github/ISSUE_TEMPLATE/bug_report.md

@@ -37,7 +37,7 @@ This questions are the first thing we need to know to understand the context.
 <!-- What do you think went wrong? -->
 
 
-**NGINX Ingress controller version** (exec into the pod and run nginx-ingress-controller --version.):
+**NGINX Ingress controller version** (exec into the pod and run `/nginx-ingress-controller --version`):
 <!--
 POD_NAMESPACE=ingress-nginx
 POD_NAME=$(kubectl get pods -n $POD_NAMESPACE -l app.kubernetes.io/name=ingress-nginx --field-selector=status.phase=Running -o jsonpath='{.items[0].metadata.name}')