CONTRIBUTING.md: don't use reST format since the file is Markdown

CONTRIBUTING.md

@@ -14,11 +14,10 @@ a lot of duplicate work.
 Write a patch
 -------------
 
-Help yourself with the `documentation <http://docs.weboob.org/>`_.
+Help yourself with the [documentation](http://docs.weboob.org/).
 
-Find an opened issue on `this website
-<https://git.weboob.org/weboob/devel/issues>`_, or write your own bugfix or
-feature. Then, once it is necessary, commit with::
+Find an opened issue on [this website](https://git.weboob.org/weboob/devel/issues),
+or write your own bugfix or feature. Then, once it is necessary, commit with:
 
     $ git commit -a
 
@@ -30,31 +29,29 @@ specific module, the first line of your commit message should read
 Check your patch
 ----------------
 
-You can run these scripts to be sure your patch doesn't break anything::
+You can run these scripts to be sure your patch doesn't break anything:
 
     $ tools/pyflakes.sh
     $ tools/weboob_lint.sh
     $ tools/run_tests.sh yourmodulename  # or without yourmodulename to test everything
 
 Perhaps you should also write or fix tests. These tests are automatically run by
-`Gitlab CI <https://git.weboob.org/weboob/devel/pipelines>`_ at each commit and merge requests.
+[Gitlab CI](https://git.weboob.org/weboob/devel/pipelines) at each commit and merge requests.
 
 
 Create a merge request or send a patch
 --------------------------------------
 
-The easiest way to send your patch is to create a fork on `the Weboob Gitlab
-<https://git.weboob.org>`_ and create a merge request from there. This way,
-the code review process is easier and continuous integration is run
+The easiest way to send your patch is to create a fork on [the Weboob
+Gitlab](https://git.weboob.org) and create a merge request from there.
+This way, the code review process is easier and continuous integration is run
 automatically (see previous section).
 
 If you prefer good old email patches, just use
 
-::
-
     $ git format-patch -n -s origin
 
-Then, send them with this command::
+Then, send them with this command:
 
     $ git send-email --to=weboob@weboob.org *.patch