minor #1865 Use version instead of url in docs (ruudk)

This PR was squashed before being merged into the 2.x branch.

Discussion
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Use version instead of url in docs

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  |no <!-- please update src/**/CHANGELOG.md files -->
| Issues        |
| License       | MIT

See symfony/symfony@1b79ae6

Commits
-------

8b67fac Use version instead of url in docs

Author: kbond

src/StimulusBundle/doc/index.rst

@@ -419,7 +419,7 @@ file::
             'path' => '@symfony/stimulus-bundle/loader.js',
         ],
         '@hotwired/stimulus' => [
-            'url' => 'https://ga.jspm.io/npm:@hotwired/stimulus@3.2.1/dist/stimulus.js',
+            'version' => '3.2.2',
         ],
     ];