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/local-timeline.ts

@@ -13,6 +13,8 @@ export const meta = {
 		'ja-JP': 'ローカルタイムラインを取得します。'
 	},
 
+	tags: ['notes'],
+
 	params: {
 		withFiles: {
 			validator: $.optional.bool,
@@ -67,6 +69,13 @@ export const meta = {
 		},
 	},
 
+	res: {
+		type: 'array',
+		items: {
+			type: 'Note',
+		},
+	},
+
 	errors: {
 		ltlDisabled: {
 			message: 'Local timeline has been disabled.',