add redis command mode desc

Author: Gowa2017

meta/3rd/skynet/library/skynet/db/redis.lua

@@ -9,36 +9,55 @@ local redis   = {}
 ---@field db integer
 ---@field username? string
 
----其他指令还可以动态生成
----更多命令查看 https://www.redis.com.cn/commands.html
+---一个 Redis 连接，返回这个 Command 对象。当在此对象上执行指令时，若指令不存在，会在第一次执行的时候构造
+---指令对象的方法。
+---指令的参数的第一个可以是 nil, 也可以是 table，还可以有多个参数。
+---异步形式，底层用 socketchannel 进行通信，这点要注意。
+---更多命令查看 [https://www.redis.com.cn/commands.html](https://www.redis.com.cn/commands.html)
+---@see socketchannel
+---@class command
 local command = {}
-function command:disconnect() end
-function command:exists(k) end
-function command:sismember(key, value) end
-function command:pipeline(ops, resp) end
+function command:disconnect()
+end
+function command:exists(k)
+end
+function command:sismember(key, value)
+end
+function command:pipeline(ops, resp)
+end
 
 --- watch mode, only can  do  SUBSCRIBE, PSUBSCRIBE, UNSUBSCRIBE, PUNSUBSCRIBE, PING  and QUIT command.
+--- we can call watch:message in endless loop.
+---@class watch
 local watch   = {}
-function watch:disconnect() end
+function watch:disconnect()
+end
 ---阻塞模式读取消息
-function watch:message() end
+function watch:message()
+end
 ---subscribe channel
-function watch:subscribe(...) end
+function watch:subscribe(...)
+end
 ---pattern subscribe channels
-function watch:psubscribe(...) end
+function watch:psubscribe(...)
+end
 ---unsubscribe
-function watch:unsubscribe(...) end
+function watch:unsubscribe(...)
+end
 ---punsubscribe
-function watch:punsubscribe(...) end
+function watch:punsubscribe(...)
+end
 
 ---connect to redis server
 ---@param conf redisconfig
 ---@return command
-function redis.connect(conf) end
+function redis.connect(conf)
+end
 
 ---connect to redis server on watch mode
 ---@param conf redisconfig
 ---@return watch
-function redis.watch(conf) end
+function redis.watch(conf)
+end
 
 return redis