Fix typo in Forked process configuration instructions

Author: tuxracer

README.md

@@ -109,7 +109,7 @@ const createStyledComponentsTransformer = require('typescript-plugin-styled-comp
 const styledComponentsTransformer = createStyledComponentsTransformer();
 
 // 3. create getCustomTransformer function
-const getCustomTransformers: () => ({ before: [styledComponentsTransformer] });
+const getCustomTransformers = () => ({ before: [styledComponentsTransformer] });
 
 // 4. export getCustomTransformers
 module.exports = getCustomTransformers;