feature #5010 Added a note about the Symfony versions affected by ICU problems (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
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Added a note about the Symfony versions affected by ICU problems

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | #4288

At first I thought about a complete rewording/simplification of this explanation, as suggested by Ryan in #4288. But then I realized that the original explanation is great and I thought that maybe we should just mention at the beginning the list of Symfony versions affected by this problem. Let me know what you think.

Commits
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8c0de1b Minow grammar fix
44f4da0 Added a note about the Symfony versions affected by ICU problems

Author: weaverryan

components/intl.rst

@@ -62,6 +62,11 @@ code::
 
 .. sidebar:: ICU and Deployment Problems
 
+    .. note::
+
+        These deployment problems only affect the following Symfony versions:
+        2.3.0 to 2.3.20 versions, any 2.4.x version and 2.5.0 to 2.5.5 versions.
+
     The intl extension internally uses the `ICU library`_ to obtain localization
     data such as number formats in different languages, country names and more.
     To make this data accessible to userland PHP libraries, Symfony ships a copy