correct some reported typos in /etc/cron.daily/apt

Closes: 702016
Reported-By: Mason Loring Bliss <mason@blisses.org>,
 Jakub Wilk <jwilk@debian.org>

debian/apt.cron.daily

@@ -91,7 +91,7 @@ check_stamp()
     stamp=$(date --date=$(date -r $stamp_file --iso-8601) +%s 2>/dev/null)
     if [ "$?" != "0" ]; then
         # Due to some timezones returning 'invalid date' for midnight on
-        # certain dates (eg America/Sao_Paulo), if date returns with error
+        # certain dates (e.g. America/Sao_Paulo), if date returns with error
         # remove the stamp file and return 0. See coreutils bug:
         # http://lists.gnu.org/archive/html/bug-coreutils/2007-09/msg00176.html
         rm -f "$stamp_file"
@@ -101,14 +101,14 @@ check_stamp()
     now=$(date --date=$(date --iso-8601) +%s 2>/dev/null)
     if [ "$?" != "0" ]; then
         # As above, due to some timezones returning 'invalid date' for midnight
-        # on certain dates (eg America/Sao_Paulo), if date returns with error
+        # on certain dates (e.g. America/Sao_Paulo), if date returns with error
         # return 0.
         return 0
     fi
 
     delta=$(($now-$stamp))
 
-    # intervall is in days, convert to sec.
+    # interval is in days, convert to sec.
     interval=$(($interval*60*60*24))
     debug_echo "check_stamp: interval=$interval, now=$now, stamp=$stamp, delta=$delta (sec)"
 
@@ -338,7 +338,7 @@ if test -r /var/lib/apt/extended_states; then
     fi
 fi
 
-# check apt-config exstance
+# check apt-config existence
 if ! which apt-config >/dev/null ; then
 	exit 0
 fi