minor #19632 [AssetMapper] Remove outdated directive from documentation (MrYamous)

This PR was merged into the 7.0 branch.

Discussion
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[AssetMapper] Remove outdated directive from documentation

Commits
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f5e545f remove outdated directive

Author: javiereguiluz

frontend/asset_mapper.rst

@@ -233,11 +233,6 @@ You can update your third-party packages to their current versions by running:
     $ php bin/console importmap:update bootstrap lodash
     $ php bin/console importmap:outdated bootstrap lodash
 
-.. versionadded:: 6.4
-
-    The ``importmap:install`` and ``importmap:outdated`` commands were introduced
-    in Symfony 6.4.
-
 How does the importmap Work?
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~