add missing empty lines in bullet lists

Signed-off-by: Alberto Pianon <alberto@pianon.eu>

contributing/reuse.rst

@@ -18,6 +18,7 @@ compliant. REUSE requires SPDX information for each file, rules for which are
 as follows:
 
 * for files copyrighted by projects contributors (**"First Party Files"**):
+
   *   any new file MUST have a SPDX header (copyright and license);
   *   for files that don't support headers (for example binaries, patches etc.) an associated ``.license`` file MUST be included with the relevant SPDX information;
   *   do not add Copyright Year as part of the SPDX header information;
@@ -26,8 +27,10 @@ as follows:
   *   you MUST NOT alter copyright statements made by others, but only add your own;
 
 * for files copyrighted by third parties and just added to the project by contributors, eg. files copied from other projects or back-ported patches (**"Third Party Files"**):
+
   * if upstream files already have SPDX headers, they MUST be left unchanged;
   * if upstream files do *not* have SPDX headers:
+  
     * the exact upstream provenance (repo, revision, path) MUST be identified;
     * you MUST NOT add SPDX headers to Third Party Files;
     * copyright and license information, as well as upstream provenance information (in the "Comment" section), MUST be stored in `.reuse/dep5` following `Debian dep5 specification <https://dep-team.pages.debian.net/deps/dep5/>`_ (see examples below);