doc/bundle: Use the more conventional suffix '.bundle'

Although it does not matter in general it is handled different by
"git clone", as it removes it to make the "humanish" name of the
new repository.
Signed-off-by: NSanti Béjar <santi@agolina.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-bundle.txt

@@ -107,17 +107,17 @@ incremental bundle,
 
 ----------------
 machineA$ cd R1
-machineA$ git bundle create file.bdl master
+machineA$ git bundle create file.bundle master
 machineA$ git tag -f lastR2bundle master
 ----------------
 
-Then you sneakernet file.bdl to the target machine B. Because you don't
+Then you sneakernet file.bundle to the target machine B. Because you don't
 have to have any object to extract objects from such a bundle, not only
 you can fetch/pull from a bundle, you can clone from it as if it was a
 remote repository.
 
 ----------------
-machineB$ git clone /home/me/tmp/file.bdl R2
+machineB$ git clone /home/me/tmp/file.bundle R2
 ----------------
 
 This will define a remote called "origin" in the resulting repository that
@@ -126,12 +126,12 @@ have an entry like this:
 
 ------------------------
 [remote "origin"]
-    url = /home/me/tmp/file.bdl
+    url = /home/me/tmp/file.bundle
     fetch = refs/heads/*:refs/remotes/origin/*
 ------------------------
 
 You can fetch/pull to update the resulting mine.git repository after
-replacing the bundle you store at /home/me/tmp/file.bdl with incremental
+replacing the bundle you store at /home/me/tmp/file.bundle with incremental
 updates from here on.
 
 After working more in the original repository, you can create an
@@ -139,11 +139,11 @@ incremental bundle to update the other:
 
 ----------------
 machineA$ cd R1
-machineA$ git bundle create file.bdl lastR2bundle..master
+machineA$ git bundle create file.bundle lastR2bundle..master
 machineA$ git tag -f lastR2bundle master
 ----------------
 
-and sneakernet it to the other machine to replace /home/me/tmp/file.bdl,
+and sneakernet it to the other machine to replace /home/me/tmp/file.bundle,
 and pull from it.
 
 ----------------