minor #15968 [String] Fix the explanation of trimPrefix and trimSuffix (javiereguiluz)

This PR was squashed before being merged into the 5.4 branch.

Discussion
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[String] Fix the explanation of trimPrefix and trimSuffix

Fixes #15951.

Commits
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38bfd69 [String] Fix the explanation of trimPrefix and trimSuffix

Author: javiereguiluz

components/string.rst

@@ -306,11 +306,16 @@ Methods to Pad and Trim
     u('   Lorem Ipsum   ')->trimStart(); // 'Lorem Ipsum   '
     u('   Lorem Ipsum   ')->trimEnd();   // '   Lorem Ipsum'
 
-    // removes the given content(s) from the start/end of the string
-    u('file-0001.png')->trimPrefix('file-');                 // '0001.png'
-    u('file-0001.png')->trimPrefix(['file-', 'image-']);     // '0001.png'
+    // removes the given content from the start/end of the string
+    u('file-image-0001.png')->trimPrefix('file-');           // 'image-0001.png'
+    u('file-image-0001.png')->trimPrefix('image-');          // 'file-image-0001.png'
+    u('file-image-0001.png')->trimPrefix('file-image-');     // '0001.png'
+    u('template.html.twig')->trimSuffix('.html');            // 'template.html.twig'
     u('template.html.twig')->trimSuffix('.twig');            // 'template.html'
-    u('template.html.twig')->trimSuffix(['.twig', '.html']); // 'template'
+    u('template.html.twig')->trimSuffix('.html.twig');       // 'template'
+    // when passing an array of prefix/sufix, only the first one found is trimmed
+    u('file-image-0001.png')->trimPrefix(['file-', 'image-']); // 'image-0001.png'
+    u('template.html.twig')->trimSuffix(['.twig', '.html']);   // 'template.html'
 
 .. versionadded:: 5.4