Update @storybook/react from 3.2.13 to 3.2.15

Author: dependencies-bot

docs/package.json

@@ -20,7 +20,7 @@
     "@storybook/addon-actions": "^3.2.15",
     "@storybook/addon-links": "^3.2.15",
     "@storybook/addons": "^3.2.15",
-    "@storybook/react": "^3.2.13",
+    "@storybook/react": "^3.2.15",
     "babel-cli": "^6.26.0",
     "babel-core": "^6.26.0",
     "babel-plugin-transform-runtime": "^6.23.0",