minor #16539 [String] Fix doc for String (nicolas-grekas)

This PR was merged into the 5.4 branch.

Discussion
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[String] Fix doc for String

Fixing #16424
`PREG_UNMATCHED_AS_NULL` is already the default and cannot be disabled.

Commits
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1f902e1 Fix doc for String

Author: javiereguiluz

components/string.rst

@@ -334,12 +334,11 @@ Methods to Search and Replace
     u('foo')->equalsTo('foo'); // true
 
     // checks if the string content match the given regular expression.
-    // You can pass flags for preg_match() as second argument. If PREG_PATTERN_ORDER
-    // or PREG_SET_ORDER are passed, preg_match_all() will be used.
     u('avatar-73647.png')->match('/avatar-(\d+)\.png/');
-    // result = ['avatar-73647.png', '73647']
-    u('avatar-73647.png')->match('/avatar-(\d+)(-\d+)?\.png/', \PREG_UNMATCHED_AS_NULL);
     // result = ['avatar-73647.png', '73647', null]
+
+    // You can pass flags for preg_match() as second argument. If PREG_PATTERN_ORDER
+    // or PREG_SET_ORDER are passed, preg_match_all() will be used.
     u('206-555-0100 and 800-555-1212')->match('/\d{3}-\d{3}-\d{4}/', \PREG_PATTERN_ORDER);
     // result = [['206-555-0100', '800-555-1212']]