minor symfony#12707 uppercase (erlangp)

This PR was submitted for the 5.0 branch but it was merged into the 4.3 branch instead (closes symfony#12707).

Discussion
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uppercase

Commits
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6ba282e uppercase

Author: OskarStark

setup.rst

@@ -237,7 +237,7 @@ stable version. If you want to use an LTS version, add the ``--version`` option:
 
 .. code-block:: terminal
 
-    # use the most recent 'lts' version
+    # use the most recent LTS version
     $ symfony new my_project_name --version=lts
 
     # use the 'next' Symfony version to be released (still in development)