Fix typos

src/libraries/luasocket/libluasocket/smtp.lua

@@ -219,7 +219,7 @@ function send_message(mesgt)
     else send_string(mesgt) end
 end
 
--- set defaul headers
+-- set default headers
 local function adjust_headers(mesgt)
     local lower = lower_headers(mesgt.headers)
     lower["date"] = lower["date"] or