[11.x] Remove mentions of Eloquent truncate from docs

eloquent.md

@@ -923,10 +923,6 @@ To delete a model, you may call the `delete` method on the model instance:
 
     $flight->delete();
 
-You may call the `truncate` method to delete all of the model's associated database records. The `truncate` operation will also reset any auto-incrementing IDs on the model's associated table:
-
-    Flight::truncate();
-
 <a name="deleting-an-existing-model-by-its-primary-key"></a>
 #### Deleting an Existing Model by its Primary Key
 

queries.md

@@ -1165,15 +1165,6 @@ The query builder's `delete` method may be used to delete records from the table
 
     $deleted = DB::table('users')->where('votes', '>', 100)->delete();
 
-If you wish to truncate an entire table, which will remove all records from the table and reset the auto-incrementing ID to zero, you may use the `truncate` method:
-
-    DB::table('users')->truncate();
-
-<a name="table-truncation-and-postgresql"></a>
-#### Table Truncation and PostgreSQL
-
-When truncating a PostgreSQL database, the `CASCADE` behavior will be applied. This means that all foreign key related records in other tables will be deleted as well.
-
 <a name="pessimistic-locking"></a>
 ## Pessimistic Locking