minor #13066 [Intl] Improve note about ext-intl. (enumag)

This PR was submitted for the master branch but it was merged into the 4.4 branch instead (closes #13066).

Discussion
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[Intl] Improve note about ext-intl.

As [requested](twigphp/Twig#3258 (comment)) by @nicolas-grekas.

Commits
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5fdffca [Intl] Improve note about ext-intl.

Author: javiereguiluz

components/intl.rst

@@ -11,7 +11,9 @@ The Intl Component
 .. caution::
 
     The replacement layer is limited to the locale "en". If you want to use
-    other locales, you should `install the intl extension`_ instead.
+    other locales, you should `install the intl extension`_. There is no conflict 
+    between the two though. Even if you use the extension this package can still
+    be useful to access the ICU data.
 
 .. seealso::