minor #12128 Add docs on Address::fromString (gisostallenberg)

This PR was squashed before being merged into the 4.4 branch (closes #12128).

Discussion
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Add docs on Address::fromString

See symfony/symfony#33086

Commits
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36960eb Add docs on Address::fromString

Author: javiereguiluz

mailer.rst

@@ -157,6 +157,15 @@ Multiple addresses are defined with the ``addXXX()`` methods::
         // ...
     ;
 
+An ``Address`` can be created from a single string::
+
+    $email = (new Email())
+        ->from(Address::fromString('Fabien <fabien@example.com>'))
+
+        // ...
+    ;
+
+
 Alternatively, you can pass multiple addresses to each method::
 
     $toAddresses = ['foo@example.com', new Address('bar@example.com')];