Correct the description of minpoll and maxpoll.
Correct the description of minpoll and maxpoll.

Note that while later versions of the ntpd documentation use the term
"dual logarithm", the text added here is consistent with the remainder
of the current document.

PR:		docs/106926
Submitted by:	Jeremy Chadwick

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase