Add redirect for yield keyword

Author: fredden

include/errors.inc

@@ -456,6 +456,7 @@ function is_known_term (string $term): ?string {
         'timestamp' => 'function.time.php',
         'try' => 'language.exceptions.php',
         'upload' => 'features.file-upload.php',
+        'yield' => 'language.generators.syntax.php#control-structures.yield',
     ];
 
     return $terms[$term] ?? null;