Removed the redundant word in a line

Author: Kaartic Sivaraam

book/07-git-tools/sections/signing.asc

@@ -179,7 +179,7 @@ Fast-forward
  1 file changed, 2 insertions(+)
 ----
 
-You can also use the `-S` option with the `git merge` command itself to sign the resulting merge commit itself.
+You can also use the `-S` option with the `git merge` command to sign the resulting merge commit itself.
 The following example both verifies that every commit in the branch to be merged is signed and furthermore signs the resulting merge commit.
 
 [source,console]