Improve docblock for with() method to clarify it adds to existing eag… (#54838)

* Improve docblock for with() method to clarify it adds to existing eager loads

The previous docblock for the with() method wasn't entirely clear on whether it set and replaced the existing eager loading list or appended to it. I had to read the source code instead of just the docblock.

This update clarifies that calling with() adds to the existing list rather than overwriting it.

* Update Builder.php

* Update Builder.php

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: igorlealantunes

src/Illuminate/Database/Eloquent/Builder.php

@@ -1595,7 +1595,7 @@ protected function createNestedWhere($whereSlice, $boolean = 'and')
     }
 
     /**
-     * Set the relationships that should be eager loaded.
+     * Specify relationships that should be eager loaded.
      *
      * @param  array<array-key, array|(\Closure(\Illuminate\Database\Eloquent\Relations\Relation<*,*,*>): mixed)|string>|string  $relations
      * @param  (\Closure(\Illuminate\Database\Eloquent\Relations\Relation<*,*,*>): mixed)|string|null  $callback