doc: perl -p -i -e s/certianly/certainly/

doc/devblog/day_-4__forgetting.mdwn

@@ -72,7 +72,7 @@ feature.
   to handle this case, too..
 
 * For some reason the automatic transitioning code triggers
-  a "(recovery from race)" commit. This is certianly a bug somewhere,
+  a "(recovery from race)" commit. This is certainly a bug somewhere,
   because you can't have a race with only 1 participant.
 
 ----

doc/devblog/day_48__direct_mode_guard_design.mdwn

@@ -3,7 +3,7 @@ Preventing a stray `git commit -a` or `git add` doing bad things in a
 direct mode repository seems increasingly important.
 
 First, considered moving `.git`, so git won't know it's a git repository.
-This doesn't seem *too* hard to do, but there will certianly be unexpected
+This doesn't seem *too* hard to do, but there will certainly be unexpected
 places that assume `.git` is the directory name.
 
 I dislike it more and more as I think about it though, because it moves

doc/devblog/day_65__wrapping_up_upgrades.mdwn

@@ -1,5 +1,5 @@
 [[!img assistant/upgradecomplete.png]]
 
 Upgrades are fully working on Linux. OSX code is written but intested and I
-thought of one bug it certianly has on my evening walk. Probably another
+thought of one bug it certainly has on my evening walk. Probably another
 hour's work left later this evening to finsh it off.

doc/devblog/day_9__Friday_the_13th.mdwn

@@ -10,7 +10,7 @@ But, I got distracted chasing down some bugs on Windows. These were
 quite ugly; more direct mode mapping breakage which resulted in 
 files not being accessible. Also fsck on Windows failed to detect and fix
 the problem. All fixed now. (If you use git-annex on Windows, you should
-certianly upgrade and run `git annex fsck`.)
+certainly upgrade and run `git annex fsck`.)
 
 As with most bugs in the Windows port, the underlying cause turned out to
 be stupid: `isSymlink` always returned False on Windows. Which makes sense