Add CMake support for also building Markdown docs in parallel (#49)

pyproject.toml

@@ -48,6 +48,8 @@ test = [
     "pytest>=7.0.0",
 ]
 
+[tool.setuptools]
+  packages = ["sphinx_llms_txt"]
 
 [tool.setuptools.dynamic]
 version = {attr = "sphinx_llms_txt.__version__"}
@@ -88,4 +90,4 @@ filterwarnings = [
     "ignore::UserWarning",
     "ignore::DeprecationWarning",
     "ignore::PendingDeprecationWarning",
-]
+]