docs: Remove trailing newlines from code blocks.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

docs/development/setup-vagrant.md

@@ -754,8 +754,8 @@ default: SSH auth method: private key
 default: Error: Connection timeout. Retrying...
 default: Error: Connection timeout. Retrying...
 default: Error: Connection timeout. Retrying...
-
 ```
+
 A likely cause is that hardware virtualization is not enabled for your
 computer. This must be done via your computer's BIOS settings. Look for a
 setting called VT-x (Intel) or (AMD-V).

docs/git/using.md

@@ -413,7 +413,6 @@ hint: Updates were rejected because the tip of your current branch is behind
 hint: its remote counterpart. Integrate the remote changes (e.g.
 hint: 'git pull ...') before pushing again.
 hint: See the 'Note about fast-forwards' in 'git push --help' for details.
-
 ```
 
 Re-running the command with `+<branch>` allows the push to continue by
@@ -429,7 +428,6 @@ Total 12 (delta 8), reused 0 (delta 0)
 remote: Resolving deltas: 100% (8/8), completed with 2 local objects.
 To git@github.com:christi3k/zulip.git
  + 2d49e2d...bfb2433 1754-docs-add-git-workflow -> 1754-docs-add-git-workflow (forced update)
-
 ```
 
 This is perfectly okay to do on your own feature branches, especially if you're

docs/production/upload-backends.md

@@ -127,7 +127,6 @@ need a block like this:
     "Action": "s3:GetObject",
     "Resource": "arn:aws:s3:::BUCKET_NAME_HERE/*"
 }
-
 ```
 
 The file-uploads bucket should not be world-readable.  See the