Add sideEffects: false to package.json (#94)

Add sideEffects: false to enable tree-shaking in bundlers

Author: neoncube2

package.json

@@ -4,6 +4,7 @@
   "description": "String#replace for React components",
   "license": "MIT",
   "main": "index.js",
+  "sideEffects": false,
   "repository": "iansinnott/react-string-replace",
   "author": {
     "name": "Ian Sinnott",
@@ -41,4 +42,4 @@
     "eslint-plugin-flowtype": "^2.25.0",
     "eslint-plugin-react": "^7.0.0"
   }
-}
+}