Typo fix unncessary -> unnecessary.

Detected while reading recent CHANGELOG entry but then decided to apply
to entire codebase and docs since why not?

doc/todo/Avoid_lengthy___34__Scanning_for_unlocked_files_...__34__/comment_13_440624874dd3697dd538655765f2b6a2._comment

@@ -3,7 +3,7 @@
  subject="""comment 13"""
  date="2021-05-31T18:40:59Z"
  content="""
-There was an unncessary check of the current time per sql insert, removing
+There was an unnecessary check of the current time per sql insert, removing
 that sped it up by 3 seconds in my benchmark.
 
 Also tried increasing the number of inserts per sqlite transaction from 1k

doc/todo/ditch_yesod.mdwn

@@ -5,7 +5,7 @@ reasons:
   painful for the android port, other builds like debian mips that don't
   currently support TH, etc. (Update: mips does support it now, it seems!)
 * I think it's responsible for at least 50% of the executable size, and I
-  suspect a lot of that is unncessary bloat for parts of yesod that
+  suspect a lot of that is unnecessary bloat for parts of yesod that
   git-annex doesn't really use.
 * Hamlet constantly annoys me by rejecting any file that contains tabs.
   **Rage**

doc/todo/dynamic_stall_detection.mdwn

@@ -9,7 +9,7 @@ flowing, it's almost certainly stalled. And if the progress display is
 updated less frequently, see if it's updated every 2 minutes, etc. Although
 realistically, progress displays are updated every chunk, and there's
 typically more than 1 chunk per minute. So longer durations than 1 minute
-may be an unncessary complication. And a minute to detect a stall is fine.
+may be an unnecessary complication. And a minute to detect a stall is fine.
 
 > Implemented this, annex.stalldetection = true enables automatic.
 

doc/todo/external_backends/comment_8_e3c66820da36fe255d07059226690ca4._comment

@@ -12,5 +12,5 @@ The suggestion that this could be used for
 [[todo/option_to_add_user-specified_string_to_key]] raises its own security
 concerns. (Although git's sha1 collision hardening probably will survive
 until git sha256, so git-annex's attempts to prevent sha1 collisions via
-user-supplied data in the content of keys are probably unncessary.)
+user-supplied data in the content of keys are probably unnecessary.)
 """]]

doc/todo/git_status_smudges_unncessarily_after_unlock.mdwn

@@ -35,5 +35,5 @@ commit -a`). Afterwards, `git status` then smudged it again, unsure why!
 > because restagePointerFile uses the git queue, and unlock 
 > also queues a git add or something, so the queue isn't able to built
 > up because two dissimilar things are being queued. This seems an
-> unncessary behavior; it could queue up all the git adds and then
+> unnecessary behavior; it could queue up all the git adds and then
 > run restagePointerFile after them all. Implemented that, and [[done]]! --[[Joey]]

doc/todo/init__58__do_not_bother_scanning_if_in_git-annex_branch.mdwn

@@ -30,5 +30,5 @@ Actually -- it made me think: is that `scanning` branch specific? then what woul
 [[!meta author=yoh]]
 [[!tag projects/datalad]]
 
-> I feel this is unncessary complexity and I've optimised the scans quite a
+> I feel this is unnecessary complexity and I've optimised the scans quite a
 > lot in the meantime, so [[wontfix|done]] --[[Joey]]

doc/todo/key_checksum_from_chunk_checksums/comment_3_352bc3eb419184a4ec70ddaffd78968e._comment

@@ -3,7 +3,7 @@
  subject="""comment 3"""
  date="2019-06-26T14:51:32Z"
  content="""
-That seems like an unusual use case that would be unncessary complication
+That seems like an unusual use case that would be unnecessary complication
 to add to git-annex, but that [[external_backends]] could be used to
 implenent as needed.
 """]]

doc/todo/may_be___40__again__41___to_prelink_or_somehow_avoid_all_the_failing_opens__63__/comment_8_b45863d81e3790ea44714a18c1721abd._comment

@@ -7,7 +7,7 @@ For details of the older todo, including some timings with and without
 prelinking, see [[!commit c4229be9a7a2318ef71b9ae433bc14bf604c9caf]].
 
 A ghc bug, since fixed, was causing it to look in IIRC, thousands of
-unncessary directories per library. This todo, by contrast, complains about
+unnecessary directories per library. This todo, by contrast, complains about
 less than 100 extra lookups total.
 
 The way you run the shim does not put the bundled git in PATH. That kind of

doc/todo/more_efficient_resolution_of_trivial_export_conflicts.mdwn

@@ -1,7 +1,7 @@
 Export conflicts happen whenever two repos export different trees 
 to the same special remote.
 
-Some conflicts that seem trivial currently involve unncessary unexporting
+Some conflicts that seem trivial currently involve unnecessary unexporting
 and re-uploading in their resolution.
 
 For example, if A exports a tree containing `[foo]`, and B exports a tree