Emit typescript declaration files

package.json

@@ -12,6 +12,7 @@
     "build": "tsc"
   },
   "main": "dist/index.js",
+  "types": "dist/index.d.ts",
   "bin": {
     "make-workout": "./bin/make-workout.js"
   },

tsconfig.json

@@ -9,6 +9,7 @@
     "noUnusedParameters": true,
     "noImplicitReturns": true,
     "noFallthroughCasesInSwitch": true,
+    "declaration": true,
   },
   "include": [
     "src/**/*"