[tz] Doubts about a typo fix

[Paul Eggert]

On 2022-11-25 19:20, Russ Allbery wrote:
> You have to be very careful with the combination of \f(CW and \fP on
> Solaris 10 nroff

That should be OK, as \f(CW - which is now \f(CR - is used only if \n(.g 
is nonzero, i.e., only if it's groff and not traditional troff.

I toyed with using \f[CW] instead of \f(CW to underscore that it's 
groff-specific. However, that might be overkill given the number of 
non-*roff programs that read these files.