Add docs

tests/type_tests.rs

@@ -2,6 +2,18 @@ pub mod common;
 
 use sea_orm::{IntoActiveValue, TryFromU64, TryGetable, Value};
 
+/*
+
+When supporting a new type in SeaORM we should implement the following traits for it:
+  - `IntoActiveValue`, given that it implemented `Into<Value>` already
+  - `TryGetable`
+  - `TryFromU64`
+
+Also, we need to update `impl FromQueryResult for JsonValue` at `src/query/json.rs`
+to correctly serialize the type as `serde_json::Value`.
+
+*/
+
 pub fn it_impl_into_active_value<T: IntoActiveValue<V>, V: Into<Value>>() {}
 
 pub fn it_impl_try_getable<T: TryGetable>() {}