DOC: fix function name

Bowen repports this typo fix about one Lua function name.

Reported-By: Bowen
diff --git a/doc/lua-api/index.rst b/doc/lua-api/index.rst
index 07e9029..e513324 100644
--- a/doc/lua-api/index.rst
+++ b/doc/lua-api/index.rst
@@ -750,7 +750,7 @@
   :param class_http http: The related http object.
   :param string query: The new query.
 
-.. js:function:: HTTP.req.set_uri(http, uri)
+.. js:function:: HTTP.req_set_uri(http, uri)
 
   Rewrites the request URI with the parameter "uri".