Fix secrets examples to be valid json

Working through the secrets example, I found some of the json descriptors to be invalid. This fixes them.

docs/user-guide/secrets/index.md

@@ -538,6 +538,7 @@ one called, say, `prod-user` with the `prod-db-secret`, and one called, say,
       }
     ]
   }
+}
 ```
 
 ### Use-case: Dotfiles in secret volume
@@ -553,7 +554,7 @@ make that key begin with a dot.  For example, when the following secret secret i
     "name": "dotfile-secret"
   },
   "data": {
-    ".secret-file": "dmFsdWUtMg0KDQo=",
+    ".secret-file": "dmFsdWUtMg0KDQo="
   }
 }
 
@@ -561,7 +562,7 @@ make that key begin with a dot.  For example, when the following secret secret i
   "kind": "Pod",
   "apiVersion": "v1",
   "metadata": {
-    "name": "secret-dotfiles-pod",
+    "name": "secret-dotfiles-pod"
   },
   "spec": {
     "volumes": [
@@ -576,7 +577,7 @@ make that key begin with a dot.  For example, when the following secret secret i
       {
         "name": "dotfile-test-container",
         "image": "gcr.io/google_containers/busybox",
-        "command": "ls -l /etc/secret-volume"
+        "command": "ls -l /etc/secret-volume",
         "volumeMounts": [
           {
             "name": "secret-volume",