Change subtitles in the introduction section to avoid having two times the same subtitles #167
Description
In the introduction section (first section) they are two times the "The transport layer" subtitles. First subsection describes what is the Transport Layer and the second subsection describes mechanisms to improve the reliability of the Transport Layer : Connectionless transport and The User Datagram Protocol. I would suggest changing this second subtitle to something like "Connectionless transport and User Datagram Protocol" or "Improving the Transport layer" to avoid confusion between the two subsection.