Show sourcemap support in typescript example

Addresses jestjs#5113

examples/typescript/preprocessor.js

@@ -6,7 +6,14 @@ const tsConfig = require('./tsconfig.json');
 module.exports = {
   process(src, path) {
     if (path.endsWith('.ts') || path.endsWith('.tsx')) {
-      return tsc.transpile(src, tsConfig.compilerOptions, path, []);
+      const {outputText, sourceMapText} = tsc.transpileModule(src, {
+        compilerOptions: tsConfig.compilerOptions,
+        fileName: path,
+        reportDiagnostics: false,
+      });
+      // Transformers can return a string with the transformed source text
+      // or a {code, map} if source maps are available
+      return {code: outputText, map: sourceMapText}
     }
     return src;
   },