More typos

[David Van Horn <dvanhorn@xxxxxxxxxx>]

Hello,

I've recently spent some time working with SRFI 19 and noticed the following 
typos in the srfi document:

time-utc->time-tai time-utc -> time-utc
    Convert UTC time to monotonic time.
time-utc->time-tai! time-utc -> time-utc
    Convert UTC time to monotonic time. The time structure may be reused.

This should read:

time-utc->time-tai time-utc -> time-tai
    Convert UTC time to TAI time.
time-utc->time-tai! time-utc -> time-tai
    Convert UTC time to TAI time. The time structure may be reused.

(Note there is a bug in both the type and textual description of the procedures.)

Also, there is an inconsistency in the way optional arguments are indicated in 
the document. Eg:

   time-tai->date time-tai . tz-offset -> date
   time-monotonic->date time-monotonic [tz-offset] -> date

Or are these supposed to mean different things?

David