Do some fixes at groups() description for it to be parsed by
Sphinx and add it to the documentation.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 Documentation/tools/kdoc_ancillary.rst | 9 +++++++++
 tools/lib/python/kdoc/c_lex.py         | 9 +++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/Documentation/tools/kdoc_ancillary.rst b/Documentation/tools/kdoc_ancillary.rst
index 3950d0a3f104..85f3806a431a 100644
--- a/Documentation/tools/kdoc_ancillary.rst
+++ b/Documentation/tools/kdoc_ancillary.rst
@@ -21,6 +21,15 @@ Regular expression class handler
    :undoc-members:
 
 
+C tokenizer
+===========
+
+.. automodule:: lib.python.kdoc.c_lex
+   :members:
+   :show-inheritance:
+   :undoc-members:
+
+
 Chinese, Japanese and Korean variable fonts handler
 ===================================================
 
diff --git a/tools/lib/python/kdoc/c_lex.py b/tools/lib/python/kdoc/c_lex.py
index b6d58bd470a9..e01b154f458e 100644
--- a/tools/lib/python/kdoc/c_lex.py
+++ b/tools/lib/python/kdoc/c_lex.py
@@ -336,13 +336,14 @@ class CTokenArgs:
         self.sub_tokeninzer = CTokenizer(sub_str)
 
     def groups(self, new_tokenizer):
-        """
+        r"""
         Create replacement arguments for backrefs like:
 
-        ``\0``, ``\1``, ``\2``, ...``\n``
+        ``\0``, ``\1``, ``\2``, ... ``\{number}``
 
-        It also accepts a ``+`` character to the highest backref. When used,
-        it means in practice to ignore delimins after it, being greedy.
+        It also accepts a ``+`` character to the highest backref, like
+        ``\4+``. When used, the backref will be greedy, picking all other
+        arguments afterwards.
 
         The logic is smart enough to only go up to the maximum required
         argument, even if there are more.
-- 
2.53.0