[tex-k] Wording improvement on A275

[胡亚捷 (Hu Yajie)]

A275, line -2 speaks of "explicit character tokens whose category
codes are respectively of types 1 and 2". But nowhere else in the book
are category codes further grouped into types. It is more reasonable to say
"explicit character tokens whose category codes are respectively 1 and 2"
or "explicit character tokens of categories 1 and 2, respectively"
or something like that.

By the way, tug.org/texmfbug/newbug.html says

    36*sqrt(2) is 50.9...; the stated approximation of 52.3 seems unusually
    imprecise.

Actually 52.3 is 37*sqrt(2) computed to one decimal place, so I think
Knuth intended to compute 36*sqrt(2) electronically but typed 37.