minor symfony#7077 remove caution message (snoek09)

This PR was submitted for the 3.1 branch but it was merged into the 2.8 branch instead (closes symfony#7077).

Discussion
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remove caution message

As discussed in symfony#6919 (comment)

Commits
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4bc8726 remove caution message

Author: xabbuh

service_container/alias_private.rst

@@ -194,8 +194,3 @@ occurrence of the ``%service_id%`` placeholder in your template.
 For service decorators (see above), if the definition does not modify the
 deprecated status, it will inherit the status from the definition that is
 decorated.
-
-.. caution::
-
-    The ability to "un-deprecate" a service is possible only when declaring the
-    definition in PHP.