Replaced caution blocks with warning

Fixes #20371

Both blocks are currently rendered identically. Keeping only one of the two makes it easier to contribute.

Some blocks were elevated to danger.

Author: TimoBakx

.doctor-rst.yaml

@@ -23,6 +23,7 @@ rules:
     forbidden_directives:
         directives:
             - '.. index::'
+            - '.. caution::'
     indention: ~
     lowercase_as_in_use_statements: ~
     max_blank_lines:

bundles.rst

@@ -3,7 +3,7 @@
 The Bundle System
 =================
 
-.. caution::
+.. warning::
 
     In Symfony versions prior to 4.0, it was recommended to organize your own
     application code using bundles. This is :ref:`no longer recommended <best-practice-no-application-bundles>` and bundles
@@ -63,7 +63,7 @@ Start by creating a new class called ``AcmeBlogBundle``::
     The :class:`Symfony\\Component\\HttpKernel\\Bundle\\AbstractBundle` was
     introduced in Symfony 6.1.
 
-.. caution::
+.. warning::
 
     If your bundle must be compatible with previous Symfony versions you have to
     extend from the :class:`Symfony\\Component\\HttpKernel\\Bundle\\Bundle` instead.
@@ -123,7 +123,7 @@ to be adjusted if needed:
 
 .. _bundles-legacy-directory-structure:
 
-.. caution::
+.. warning::
 
     The recommended bundle structure was changed in Symfony 5, read the
     `Symfony 4.4 bundle documentation`_ for information about the old