bug#1381: 23.0.60; capitalization of car and cdr in the doc

[Richard M. Stallman]

    OK, that's one thing. But my question was whether these shouldn't simply be
    treated as normal Emacs terms - just like cons, buffer, symbol, and frame, 
after
    they have been introduced (defined).

The reason for using @sc on car and cdr is that they are acronyms.
Those other terms are not acronyms.