minor #19425 [Scheduler] Emphasize __toString() (alexandre-daubois)

This PR was merged into the 6.3 branch.

Discussion
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[Scheduler] Emphasize `__toString()`

Fix #18250

The information is already present but we can emphasize the need to implement this option. What do you think?

Commits
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fa15a7a [Scheduler] Emphasize `__toString()`

Author: javiereguiluz

scheduler.rst

@@ -189,6 +189,8 @@ For example, if you want to send customer reports daily except for holiday perio
 
         public function __toString(): string
         {
+            // give a nice displayable name to your trigger
+            // to ease debugging
             return $this->inner.' (except holidays)';
         }