doc: Enable TODOs

Signed-off-by: Rahix <rahix@rahix.de>

.gitignore

@@ -3,3 +3,4 @@ build/
 __pycache__/
 *.pyc
 .*.swp
+*~

Documentation/conf.py

@@ -37,8 +37,11 @@ extensions = [
     "sphinx.ext.autodoc",
     "sphinx.ext.viewcode",
     "sphinx.ext.ifconfig",
+    "sphinx.ext.todo",
 ]
 
+todo_include_todos = True
+
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
 # This pattern also affects html_static_path and html_extra_path.