cli: Add --list-files command line option

This option lists the files to lint by yamllint, taking into account `ignore`
and `yaml-files` configuration options.

docs/configuration.rst

@@ -136,6 +136,13 @@ directories, set ``yaml-files`` configuration option. The default is:
 The same rules as for ignoring paths apply (``.gitignore``-style path pattern,
 see below).
 
+If you need to know the exact list of files that yamllint would process,
+without really linting them, you can use ``--list-files``:
+
+.. code:: bash
+
+ yamllint --list-files .
+
 Ignoring paths
 --------------
 
@@ -220,6 +227,13 @@ or:
 
 .. note:: However, this is mutually exclusive with the ``ignore`` key.
 
+If you need to know the exact list of files that yamllint would process,
+without really linting them, you can use ``--list-files``:
+
+.. code:: bash
+
+ yamllint --list-files .
+
 Setting the locale
 ------------------