*: fix typos which duplicate a word

Fix typos in documentation, code comments, and RelNotes which repeat
various words.  In trivial cases, just delete the duplicated word and
rewrap text, if needed.  Reword the affected sentence in
Documentation/RelNotes/1.8.4.txt for it to make sense.

Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/RelNotes/1.6.0.3.txt

@@ -50,7 +50,7 @@ Fixes since v1.6.0.2
   if the working tree is currently dirty.
 
 * "git for-each-ref --format=%(subject)" fixed for commits with no
-  no newline in the message body.
+  newline in the message body.
 
 * "git remote" fixed to protect printf from user input.
 

Documentation/RelNotes/1.8.4.txt

@@ -365,7 +365,7 @@ details).
    (merge 2fbd4f9 mh/maint-lockfile-overflow later to maint).
 
  * Invocations of "git checkout" used internally by "git rebase" were
-   counted as "checkout", and affected later "git checkout -" to the
+   counted as "checkout", and affected later "git checkout -", which took
    the user to an unexpected place.
    (merge 3bed291 rr/rebase-checkout-reflog later to maint).
 

Documentation/RelNotes/2.29.0.txt

@@ -184,8 +184,8 @@ Performance, Internal Implementation, Development Support etc.
    the ref backend in use, as its format is much richer than the
    normal refs, and written directly by "git fetch" as a plain file..
 
- * An unused binary has been discarded, and and a bunch of commands
-   have been turned into into built-in.
+ * An unused binary has been discarded, and a bunch of commands
+   have been turned into built-in.
 
  * A handful of places in in-tree code still relied on being able to
    execute the git subcommands, especially built-ins, in "git-foo"

Documentation/RelNotes/2.8.0.txt

@@ -377,7 +377,7 @@ notes for details).
    on that order.
 
  * "git show 'HEAD:Foo[BAR]Baz'" did not interpret the argument as a
-   rev, i.e. the object named by the the pathname with wildcard
+   rev, i.e. the object named by the pathname with wildcard
    characters in a tree object.
    (merge aac4fac nd/dwim-wildcards-as-pathspecs later to maint).