Update type.md

Author: ColinH

doc/ref/type.md

@@ -1,4 +1,4 @@
-### `tao::json::type`
+## `tao::json::type`
 
 Defined in `<tao/json/type.hh>`
 
@@ -19,8 +19,20 @@ enum class type : std::uint8_t
 };
 ```
 
-Specifies which contents is currently stored in a [`basic_value`](basic_value.md).
+For tracking the kind of data currently stored in a [`basic_value`](basic_value.md).
 
-#### Constants
+### Constants
 
-TODO
+| Name | Description |
+| --- | --- |
+| `UNINITIALIZED` | For [`basic_value`](basic_value.md)s that have not been assigned a value, or that have been `reset`. |
+| `DISCARDED` | For [`basic_value`](basic_value.md)s that have been discarded, either explicitly or after being *moved*. |
+| `NULL_` | For JSON null values. |
+| `BOOLEAN` | For JSON boolean values. |
+| `SIGNED` | For JSON numbers stored as `std::int64_t`. |
+| `UNSIGNED` | For JSON numbers stored as `std::uint64_t`. |
+| `DOUBLE` | For JSON numbers stored as `double`' |
+| `STRING` | For JSON strings. |
+| `ARRAY` | For JSON arrays. |
+| `OBJECT` | For JSON objects. |
+| `RAW_PTR` | For [`basic_value`](basic_value.md)s that wrap a plain pointer to a different [`basic_value`](basic_value.md). |