fix(doc): fix typos in edgex meta tutorial

Signed-off-by: Jiyong Huang <huangjy@emqx.io>

docs/en_US/edgex/edgex_meta.md

@@ -87,8 +87,7 @@ SELECT temperature,humidity, meta(id) AS eid,meta(origin) AS eo, meta(temperatur
 
 ## Summary
 
-`meta` function can be used in eKuiper to access metadata values. Below lists all available keys for `Events` and `Reading`.
-
-- Events: id, deviceName, profileName, sourceName, origin, tags, correlationid
-- Readning: id, deviceName, profileName, origin, valueType
+`meta` function can be used in eKuiper to access metadata values. Below lists all available keys for `Event` and `Reading`.
 
+- Event: id, deviceName, profileName, sourceName, origin, tags, correlationid
+- Reading: id, deviceName, profileName, origin, valueType

docs/zh_CN/edgex/edgex_meta.md

@@ -87,7 +87,7 @@ SELECT temperature,humidity, meta(id) AS eid,meta(origin) AS eo, meta(temperatur
 
 ## 总结
 
-Kuper 的 `meta` 函数可以用于访问元数据，以下列出了所有在 EdgeX 的 `Events` 和 `Reading` 中支持的 key，
+Kuper 的 `meta` 函数可以用于访问元数据，以下列出了所有在 EdgeX 的 `Event` 和 `Reading` 中支持的 key，
 
-- Events: id, deviceName, profileName, sourceName, origin, tags, correlationid
-- Readning: id, deviceName, profileName, origin, valueType
+- Event: id, deviceName, profileName, sourceName, origin, tags, correlationid
+- Reading: id, deviceName, profileName, origin, valueType