kernel: fixup Go kernel display name

This CL fixes the display name of the Go kernel:
Go is called Go, not Golang.

Author: sbinet

README.md

@@ -164,7 +164,7 @@ Then:
         "/Users/<your username>/go/bin/gophernotes",
         "{connection_file}"
         ],
-      "display_name": "Golang",
+      "display_name": "Go",
       "language": "go",
       "name": "go"
   }

kernel/kernel.json

@@ -3,7 +3,7 @@
 		"gophernotes",
     	"{connection_file}"
     	],
-    "display_name": "Golang",
+    "display_name": "Go",
     "language": "go",
     "name": "go"
 }