nixpkgs docs: format =)

doc/contributing.xml

@@ -1,35 +1,35 @@
 <chapter xmlns="http://docbook.org/ns/docbook"
          xmlns:xlink="http://www.w3.org/1999/xlink"
          xml:id="chap-contributing">
-
-<title>Contributing to this documentation</title>
-
-<para>The DocBook sources of the Nixpkgs manual are in the <filename
+ <title>Contributing to this documentation</title>
+ <para>
+  The DocBook sources of the Nixpkgs manual are in the
+  <filename
 xlink:href="https://github.com/NixOS/nixpkgs/tree/master/doc">doc</filename>
-subdirectory of the Nixpkgs repository.</para>
-
-<para>You can quickly check your edits with <command>make</command>:</para>
-
+  subdirectory of the Nixpkgs repository.
+ </para>
+ <para>
+  You can quickly check your edits with <command>make</command>:
+ </para>
 <screen>
   $ cd /path/to/nixpkgs/doc
   $ nix-shell
   [nix-shell]$ make
 </screen>
-
-<para>If you experience problems, run <command>make debug</command>
-to help understand the docbook errors.</para>
-
-<para>After making modifications to the manual, it's important to
-build it before committing. You can do that as follows:
-
+ <para>
+  If you experience problems, run <command>make debug</command> to help
+  understand the docbook errors.
+ </para>
+ <para>
+  After making modifications to the manual, it's important to build it before
+  committing. You can do that as follows:
 <screen>
   $ cd /path/to/nixpkgs/doc
   $ nix-shell
   [nix-shell]$ make clean
   [nix-shell]$ nix-build .
 </screen>
-
-If the build succeeds, the manual will be in
-<filename>./result/share/doc/nixpkgs/manual.html</filename>.</para>
-
+  If the build succeeds, the manual will be in
+  <filename>./result/share/doc/nixpkgs/manual.html</filename>.
+ </para>
 </chapter>