Add name of lecture to order completed mail

Currently after the order process the lecturer receives an email with all relevant information which he/she submitted. Since these do not contain the name of the lecture it is easy to mix them up.

No file or test is named. Start by locating the order-completion email entry point and the lecture data passed into it; confirm how the lecturer's submitted information is assembled. Done means the completed-order email clearly includes the lecture name so different orders can be distinguished.

Written by the indexing model from the issue text.