minor #17239 [Form] Fix Bootstrap 5 section indentation (ker0x)

This PR was merged into the 5.4 branch.

Discussion
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[Form] Fix Bootstrap 5 section indentation

Commits
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b41941d [Form] Fix Bootstrap 5 section indentation

Author: xabbuh

form/bootstrap5.rst

@@ -101,7 +101,7 @@ For a checkbox/radio field, calling ``form_label()`` doesn't render anything.
 Due to Bootstrap internals, the label is already rendered by ``form_widget()``.
 
 Inline Checkboxes and Radios
-----------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 If you want to render your checkbox or radio fields `inline`_, you can add
 the ``checkbox-inline`` or ``radio-inline`` class (depending on your Symfony
@@ -138,7 +138,7 @@ Form type or ``ChoiceType`` configuration) to the label class.
         }) }}
 
 Switches
-________
+~~~~~~~~
 
 Bootstrap 5 allows to render checkboxes as `switches`_. You can enable this
 feature on your Symfony Form ``CheckboxType`` by adding the ``checkbox-switch``
@@ -178,7 +178,7 @@ class to the label:
     Switches only work with **checkbox**.
 
 Input group
-___________
+-----------
 
 To create `input group`_ in your Symfony Form, simply add the ``input-group``
 class to the ``row_attr`` option.