changelog: variable 'writen' is changed

This patch change the variable name to 'written' in changelog, along
with few other typo fixing.

Change-Id: I1d3cbea5c89fc0a15233bb6e61b4fbd4bfdd3a67
BUG: 1075417
Signed-off-by: Humble Chirammal <hchiramm@redhat.com>
Reviewed-on: http://review.gluster.org/8267
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>
Tested-by: Venky Shankar <vshankar@redhat.com>