fix typo: copyt->copy (fastai#419)

02_production.ipynb

@@ -1774,7 +1774,7 @@
     "2. Paste the URL of that repo into Binder's URL, as shown in <<deploy-binder>>.\n",
     "3. Change the File dropdown to instead select URL.\n",
     "4. In the \"URL to open\" field, enter `/voila/render/name.ipynb` (replacing `name` with the name of for your notebook).\n",
-    "5. Click the clickboard button at the bottom right to copyt the URL and paste it somewhere safe. \n",
+    "5. Click the clickboard button at the bottom right to copy the URL and paste it somewhere safe. \n",
     "6. Click Launch."
    ]
   },