changed composite url

Author: Gabefire

examples/exports/composite_mask_export.ipynb

@@ -87,7 +87,7 @@
       "source": [
         "### Composite masks\n",
         "**IMPORTANT :** The URL for the ```composite_mask``` from exports older than 30 days will no longer be accessible. To obtain a functional URL after this period, please generate a new export for the mask.\n",
-        "1. A single mask URL contains all mask instances from a single label. For videos a composite mask contains all mask instances for the frame in each label. \n",
+        "1. A composite URL contains all mask instances from a single label. For videos a composite mask contains all mask instances per frame in each label. \n",
         "2. The export and mask URL adheres to the following convention:\n",
         "  - ***Image example***\n",
         "```json \n",