feat: Cornerstone extension viewport default enabledElement handler and installation guides (#2636)

* feat: Add initial doc for mode installation

* fix: cornerstone viewport should have default enabledElement handler

* docs: Add custom mode and extension installation guides

* docs: Add route address for template mode

.webpack/webpack.base.js

@@ -34,7 +34,7 @@ module.exports = (env, argv, { SRC_DIR, DIST_DIR }) => {
 
   const config = {
     mode: isProdBuild ? 'production' : 'development',
-    devtool: isProdBuild ? 'source-map' : 'eval',
+    devtool: isProdBuild ? 'source-map' : 'eval-source-map',
     entry: {
       app: `${SRC_DIR}/index.js`,
     },