Remove extra newlines at the beginning/end of files

Those are redundant, and yaml parser strips them in fact. By removing
them, loading and saving yaml file without any change indeed produce the
same output. This is useful for prepare_for_translation.py script (which
adds lang and ref tags) - to produce only change that indeed was made.

developer/code/code-signing.md

@@ -6,7 +6,6 @@ ref: 51
 title: Code Signing
 ---
 
-
 All contributions to the Qubes OS [source code](/doc/source-code/) must be cryptographically signed by the author's PGP key.
 
 ## Generating a Key
@@ -202,4 +201,3 @@ Please upload it.
 If you're submitting a patch by emailing the [developer mailing list](/support/#qubes-devel), simply sign your email with your PGP key.
 One good way to do this is with a program like [Enigmail](https://www.enigmail.net/).
 Enigmail is a security addon for the Mozilla Thunderbird email client that allows you to easily digitally encrypt and sign your emails.
-

developer/code/coding-style.md

@@ -11,7 +11,6 @@ ref: 53
 title: Coding Style
 ---
 
-
 Rationale
 ---------
 

developer/code/license.md

@@ -10,7 +10,6 @@ ref: 52
 title: Software License
 ---
 
-
 Qubes is a compilation of software packages, each under its own license. The compilation is made available under the GNU General Public License version 2.
 
 The full text of the GPL v2 license can be found [here](https://www.gnu.org/licenses/gpl-2.0.html).

developer/code/source-code.md

@@ -10,7 +10,6 @@ ref: 54
 title: Source Code
 ---
 
-
 All the Qubes code is kept in Git repositories. We have divided the project into
 several components, each of which has its own separate repository, for example:
 
@@ -81,4 +80,3 @@ method you choose, you must [sign your code](/doc/code-signing/) before it can b
       name and email, so that *your* name will be used as a commit's author.
    5. Send your patch to `qubes-devel`. Start the message subject with
       `[PATCH]`.
-