Merge pull request #180 from storybookjs/yann/add-types

Enable TypeScript declaration generation

Author: yannbf

tsconfig.build.json

@@ -7,7 +7,8 @@
     "forceConsistentCasingInFileNames": true,
     "strict": true,
     "skipLibCheck": true,
-    "noUncheckedIndexedAccess": true
+    "noUncheckedIndexedAccess": true,
+    "declaration": true
   },
   "ts-node": {
     "transpileOnly": true