Reword introduction

Author: Mathieu

reference/constraints/NoSuspiciousCharacters.rst

@@ -5,15 +5,25 @@ NoSuspiciousCharacters
 
     The ``NoSuspiciousCharacters`` constraint was introduced in Symfony 6.3.
 
-A good thing about Unicode is that it allows to use (almost) every imaginable character.
-A bad thing is that this makes spoofing rather easy: "symfony.com" and "ѕymfony.com"
-look similar, but the latter actually starts with a `cyrillic small letter dze`_.
+..
+
+    Because Unicode contains such a large number of characters and incorporates
+    the varied writing systems of the world, incorrect usage can expose programs
+    or systems to possible security attacks.
+
+    `Unicode® Technical Standard #39`_
+
+"symfony.com" and "ѕymfony.com" look similar, but the latter actually starts with a
+`cyrillic small letter dze`_. It could make a user think they'll navigate to Symfony's
+website, whereas it would be somewhere else.
+This is a kind of `spoofing attack`_ (called "IDN homograph attack"): it tries to
+identify something as something else to exploit the resulting confusion.
 This is why it is recommended to check user-submitted, public-facing identifiers for
-suspicious characters to prevent spoofing attempts.
+suspicious characters in order to prevent such attacks.
 
-This constraint performs such validation on strings or :phpclass:`Stringable`s.
-As it leverages PHP's :phpclass:`Spoofchecker`, the intl extension must be enabled to
-use it.
+This constraint ensures strings or :phpclass:`Stringable`s do not include any
+suspicious characters. As it leverages PHP's :phpclass:`Spoofchecker`, the intl
+extension must be enabled to use it.
 
 ==========  ===================================================================
 Applies to  :ref:`property or method <validation-property-target>`
@@ -138,7 +148,9 @@ You can accept all characters by setting this option to
 
 .. include:: /reference/constraints/_payload-option.rst.inc
 
+.. _`Unicode® Technical Standard #39`: https://unicode.org/reports/tr39/
 .. _`cyrillic small letter dze`: https://graphemica.com/%D1%95
+.. _`spoofing attack`: https://en.wikipedia.org/wiki/Spoofing_attack
 .. _`single-script`: https://unicode.org/reports/tr39/#def-single-script
 .. _`covered`: https://unicode.org/reports/tr39/#def-cover
 .. _`Recommended`: https://www.unicode.org/reports/tr31/#Table_Recommended_Scripts