man: change lexical to lexicographic

man: change lexical to lexicographic

This changes the instances of lexical to lexicographic, thus making it easier
to grep for instances of lexicographic order, since there's only one variant of
the word to consider.

Lexicographic is chosen since there are slightly fewer instances of lexical and
lexicographic seems a better fit than lexical after checking a few
dictionaries.

The words lexical, lexicographic, and lexicographical are synonyms in
computing, meaning an alphabetical order. Both the Oxford dictionary and
Merriam-Webster make no distinction between lexicographic and lexicographical,
with only Wiktionary adding a more precise meaning of

    Meeting lexicographical standards or requirements; worthy of being included
    in a dictionary. [1]

Since, outside of computing, lexicographic(al) has the more specific meaning
pertaining to lexicography, i.e. the editing or making of dictionaries [2], and
lexical only has this as a secondary meaning after its linguistic meaning [3],
lexicographic fits the meaning of including and ordering entries better.

[1] https://en.wiktionary.org/wiki/lexicographical#English
[2] https://www.merriam-webster.com/dictionary/lexicographic
[3] https://www.oed.com/dictionary/lexical_adj