Tweaks into AccountingStart documentation.

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>

doc/tor.1.txt

@@ -2173,7 +2173,7 @@ is non-zero):
     Specify how long accounting periods last. If **month** is given,
     each accounting period runs from the time __HH:MM__ on the __dayth__ day of one
     month to the same day and time of the next. The relay will go at full speed,
-    use all the quota you specify, then hibernate for the rest of the month.(The
+    use all the quota you specify, then hibernate for the rest of the period. (The
     day must be between 1 and 28.) If **week** is given, each accounting period
     runs from the time __HH:MM__ of the __dayth__ day of one week to the same day
     and time of the next week, with Monday as day 1 and Sunday as day 7. If **day**