minor #1011 Update index.rst regex matching file extensions fix (gpetraroli)

This PR was merged into the 2.x branch.

Discussion
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Update index.rst regex matching file extensions fix

 /\\.(j|t)sx?$/. It seems to be using double backslashes (\\) to escape the dot (.) character, which is not necessary. The correct way to escape the dot character in a regular expression is by using a single backslash (\), like this: /\.(j|t)sx?$/.

Commits
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f455802 Update index.rst regex matching file extensions fix

Author: weaverryan

src/React/doc/index.rst

@@ -54,7 +54,7 @@ code to your ``assets/app.js`` file:
     // assets/app.js
     import { registerReactControllerComponents } from '@symfony/ux-react';
 
-    registerReactControllerComponents(require.context('./react/controllers', true, /\\.(j|t)sx?$/));
+    registerReactControllerComponents(require.context('./react/controllers', true, /\.(j|t)sx?$/));
 
 This will load all React components located in the ``assets/react/controllers``
 directory. These are known as **React controller components**: top-level