👷(ci) put storybook build in a gh-pages sub folder

Our main goal doing this is to allow us to have multiple static build
standing next to each other on our gh-pages.

scripts/predeploy-ghpages

@@ -0,0 +1,9 @@
+rm -rf ghpages-output
+mkdir -p ghpages-output/storybook
+
+cd packages/react && yarn build-storybook
+cd ../..
+mv packages/react/storybook-static/* ghpages-output/storybook
+
+touch ./ghpages-output/.nojekyll
+touch ./ghpages-output/storybook/.nojekyll