Update object-attribute-reference.md

Add a reserved attributes Table

docs/object-attribute-reference.md

@@ -1,13 +1,20 @@
 # Object Attribute Reference
-## List all preset object attributes
+## List all **USABLE** preset object attributes
 
 | Attribute         | Type      | Value | Description |
 |-------------------|-----------|-------|-------------|
 | `xp`              | function  | `exerciceExpCalculation`, `examExpCalculation` or `raidExpCalculation` | Amount of exeperience points that an object will give. |
 | `correctionPrice` | function  | `correctionPrice` | Amount of correction points needed to test an exercise. |
+| `duration`        | number    | | |
+| `time`            | string    | | |
+| `info`            | object    | | |
+
+## List all **RESERVED** preset object attributes
+
+| Attribute         | Type      | Value | Description |
+|-------------------|-----------|-------|-------------|
 | `scopeStart`      | function  | | |
 | `scopeEnd`        | function  | | |
 | `startDay`        | function  | | |
 | `status`          | function  | | |
-| `time`            | string    | | |
 | `week`            | function  | | |