✨ add plugin metadata to builtin plugins (#2113)

nonebot/plugins/echo.py

@@ -1,7 +1,18 @@
+from nonebot import on_command
 from nonebot.rule import to_me
 from nonebot.adapters import Message
 from nonebot.params import CommandArg
-from nonebot.plugin import on_command
+from nonebot.plugin import PluginMetadata
+
+__plugin_meta__ = PluginMetadata(
+    name="echo",
+    description="重复你说的话",
+    usage="/echo [text]",
+    type="application",
+    homepage="https://github.com/nonebot/nonebot2/blob/master/nonebot/plugins/echo.py",
+    config=None,
+    supported_adapters=None,
+)
 
 echo = on_command("echo", to_me())
 

nonebot/plugins/single_session.py

@@ -2,8 +2,19 @@ from typing import Dict, AsyncGenerator
 
 from nonebot.adapters import Event
 from nonebot.params import Depends
+from nonebot.plugin import PluginMetadata
 from nonebot.message import IgnoredException, event_preprocessor
 
+__plugin_meta__ = PluginMetadata(
+    name="唯一会话",
+    description="限制同一会话内同时只能运行一个响应器",
+    usage="加载插件后自动生效",
+    type="application",
+    homepage="https://github.com/nonebot/nonebot2/blob/master/nonebot/plugins/single_session.py",
+    config=None,
+    supported_adapters=None,
+)
+
 _running_matcher: Dict[str, int] = {}