minor symfony#2274 Update index.rst (GrinWay)

This PR was merged into the 2.x branch.

Discussion
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Update index.rst

Fixed forgotten commas in twig component function, cuz without it... It won't be working

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| Issues        | Fix the documentation
| License       | MIT

Commits
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d6bb6d7 Update index.rst

Author: javiereguiluz

src/LiveComponent/doc/index.rst

@@ -2421,7 +2421,7 @@ the ``loading-template`` option to point to a template:
     <twig:SomeHeavyComponent loading="defer" loading-template="spinning-wheel.html.twig" />
 
     {# With the component function #}
-    {{ component('SomeHeavyComponent', { loading: 'defer', loading-template: 'spinning-wheel.html.twig' }) }}
+    {{ component('SomeHeavyComponent', { loading: 'defer', 'loading-template': 'spinning-wheel.html.twig' }) }}
 
 Or override the ``loadingContent`` block:
 
@@ -2444,7 +2444,7 @@ To change the initial tag from a ``div`` to something else, use the ``loading-ta
 
 .. code-block:: twig
 
-    {{ component('SomeHeavyComponent', { loading: 'defer', loading-tag: 'span' }) }}
+    {{ component('SomeHeavyComponent', { loading: 'defer', 'loading-tag': 'span' }) }}
 
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