NaCl docs: fix a few more issues with the ARM sandbox documentation.

chrome/common/extensions/docs/templates/json/chrome_sidenav.json

 [
   {
     "title": "Devtools",
     "items": [
       {
         "title": "Learn Basics",
         "items": [
           {
             "title": "Overview",
             "href": "/devtools/index.html"
@@ skipping 812 matching lines @@
                 "title": "PNaCl Bitcode Reference Manual",
                 "href": "/native-client/reference/pnacl-bitcode-abi.html"
               },
               {
                 "title": "PNaCl C/C++ Language Support",
                 "href": "/native-client/reference/pnacl-c-cpp-language-support.html"
               },
               {
                 "title": "Previous Versions",
                 "href": "/native-client/version.html"
+              },
+              {
+                "title": "Sandbox Internals",
+                "href": "/native-client/reference/sandbox_internals/index.html",
+                "items": [
+                    {
+                      "title": "ARM 32-bit Sandbox",
+                      "href": "/native-client/reference/sandbox_internals/arm-32-bit-sandbox.html"
+                    }
+                ]
               }
             ]
           },
           {
             "title": "Help",
             "href": "/native-client/faq.html",
             "items": [
               {
                 "title": "FAQ",
                 "href": "/native-client/faq.html"
@@ skipping 119 matching lines @@
                 "title": "Articles",
                 "href": "/webstore/articles.html"
               }
             ]
           }
         ]
       }
     ]
   }
 ]