doc: fixed a typo in the doc for coroutine.yield(). thanks Ruoshan Huang for the report.

Author: agentzh

README.markdown

@@ -5882,7 +5882,7 @@ This API was first introduced in the `v0.6.0` release.
 
 coroutine.yield
 ---------------
-**syntax:** *... = coroutine.yield(co, ...)*
+**syntax:** *... = coroutine.yield(...)*
 
 **context:** *rewrite_by_lua*, access_by_lua*, content_by_lua*, init_by_lua*, ngx.timer.**
 

doc/HttpLuaModule.wiki

@@ -4993,7 +4993,7 @@ This API was first usable in the context of [[#init_by_lua|init_by_lua*]] since
 This API was first introduced in the <code>v0.6.0</code> release.
 
 == coroutine.yield ==
-'''syntax:''' ''... = coroutine.yield(co, ...)''
+'''syntax:''' ''... = coroutine.yield(...)''
 
 '''context:''' ''rewrite_by_lua*, access_by_lua*, content_by_lua*, init_by_lua*, ngx.timer.*''