CMH: Clarify that EOL indicates the end the options in the per-fragment option area just as it does in the per-datagram surplus area

[Mike-Heard]

Martin Duke pointed out that the description of EOL does not stipulate that it terminates the per-fragment options area (see https://mailarchive.ietf.org/arch/msg/tsvwg/8JBqbYF_fZp6MBhNVzuNMSGr4as/). This is easily fixed with the following change throughout Section 11.1:

s/surplus area/surplus area or the options area in a UDP fragment/