Add redirects for moved troubleshooting pages

Redirect old /docs/troubleshooting/templates/* URLs to their new
locations under /docs/troubleshooting/.

Author: beran-t

docs.json

@@ -284,6 +284,16 @@
     }
   },
   "redirects": [
+    {
+      "source": "/docs/troubleshooting/templates/build-authentication-error",
+      "destination": "/docs/troubleshooting/build-authentication-error",
+      "permanent": true
+    },
+    {
+      "source": "/docs/troubleshooting/templates/49999-port-not-open",
+      "destination": "/docs/troubleshooting/49999-port-not-open",
+      "permanent": true
+    },
     {
       "source": "/docs/template/aliases",
       "destination": "/docs/template/names",