minor #19109 [Testing] [Panther] Add component documentation (alexandre-daubois)

This PR was merged into the 6.4 branch.

Discussion
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[Testing] [Panther] Add component documentation

Fix #12200

Had a quick chat with `@OskarStark` about adding complete documentation of Panther or not. As the [README](https://github.com/symfony/panther/blob/main/README.md) of the project is already full and well written, we thought it may deserve a mention in the Testing page rather than a full documentation page (which would only repeat the README after all)

Commits
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5411430 [Panther] Add component documentation

Author: javiereguiluz

.doctor-rst.yaml

@@ -111,4 +111,4 @@ whitelist:
         - '.. versionadded:: 3.6' # MonologBundle
         - '.. versionadded:: 3.8' # MonologBundle
         - '.. _`a feature to test applications using Mercure`: https://github.com/symfony/panther#creating-isolated-browsers-to-test-apps-using-mercure-or-websocket'
-        - '..  End to End Tests (E2E)'
+        - 'End to End Tests (E2E)'

testing.rst

@@ -1166,12 +1166,15 @@ HttpClient Assertions
 
     The HttpClient assertions were introduced in Symfony 6.4.
 
-.. TODO
-..  End to End Tests (E2E)
-..  ----------------------
-..  * panther
-..  * testing javascript
-..  * UX or form collections as example?
+End to End Tests (E2E)
+~~~~~~~~~~~~~~~~~~~~~~
+
+If you need to test the application as a whole, including the JavaScript
+code, you can use a real browser instead of the test client. This is
+called an end-to-end test and it's a great way to test the application.
+
+This can be achieved thanks to the Panther component. You can learn more
+about it in :doc:`the dedicated page </testing/end_to_end>`.
 
 Learn more
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