Make all external links in the documentation open in a new window

To make it easier to stay on track when reading documentation, I
added ",role=external,window=_blank" to all links in the
documentation directory that were not pointing at another piece of documentation.

Change-Id: I94bf254c90f8ebce067c765be0a2932b755a045a

Documentation/error-push-fails-due-to-commit-message.txt

diff --git a/Documentation/error-push-fails-due-to-commit-message.txt b/Documentation/error-push-fails-due-to-commit-message.txt
index f6e5c1f..ba941e5 100644
--- a/Documentation/error-push-fails-due-to-commit-message.txt
+++ b/Documentation/error-push-fails-due-to-commit-message.txt
@@ -6,7 +6,7 @@
 
 If the commit message of the last commit needs to be fixed you can
 simply amend the last commit (please find a detailed description in
-the link:http://www.kernel.org/pub/software/scm/git/docs/git-commit.html[Git documentation]):
+the link:http://www.kernel.org/pub/software/scm/git/docs/git-commit.html[Git documentation,role=external,window=_blank]):
 
 ----
   $ git commit --amend
@@ -17,7 +17,7 @@
 rebase for the affected commits. While doing the interactive rebase
 you can e.g. choose 'reword' for those commits for which you want to
 fix the commit messages. For a detailed description of git rebase
-please check the link:http://www.kernel.org/pub/software/scm/git/docs/git-rebase.html[Git documentation].
+please check the link:http://www.kernel.org/pub/software/scm/git/docs/git-rebase.html[Git documentation,role=external,window=_blank].
 
 Please use interactive git rebase with care as it rewrites existing
 commits. Generally you should never rewrite commits that have already