minor #12790 Fix UnicodeString::before() example (jdreesen)

This PR was merged into the 5.0 branch.

Discussion
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Fix `UnicodeString::before()` example

If I'm not mistaken, the result of `u('hello world')->before('o');` would be `'hell'` instead of `'hell '`.

Commits
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9322a00 Fix output of before() example

Author: javiereguiluz

components/string.rst

@@ -238,7 +238,7 @@ Methods to Append and Prepend
 
     // returns the contents found before/after the first occurrence of the given string
     u('hello world')->before('world');   // 'hello '
-    u('hello world')->before('o');       // 'hell '
+    u('hello world')->before('o');       // 'hell'
     u('hello world')->before('o', true); // 'hello'
 
     u('hello world')->after('hello');   // ' world'