Introduce OpenAPI specs (#4351)

* wip

* wip

* wip

* Update index.ts

* Update gen-openapi-spec.ts

* Update api.ja-JP.md

* Fix

* Improve doc

* Update gen-openapi-spec.ts

* Update redoc.html

* Improve doc

* Update gen-openapi-spec.ts

* Improve doc

* Update CHANGELOG.md

src/server/api/endpoints/notes/user-list-timeline.ts

@@ -14,6 +14,8 @@ export const meta = {
 		'en-US': 'Get timeline of a user list.'
 	},
 
+	tags: ['notes', 'lists'],
+
 	requireCredential: true,
 
 	params: {
@@ -102,6 +104,13 @@ export const meta = {
 		},
 	},
 
+	res: {
+		type: 'array',
+		items: {
+			type: 'Note',
+		},
+	},
+
 	errors: {
 		noSuchList: {
 			message: 'No such list.',