doc(hansbug): Add doc framework for numpy and utils

docs/source/api_doc/numpy/funcs.rstc

+treetensor.numpy.funcs
\ No newline at end of file

docs/source/api_doc/numpy/index.rst

+treetensor.numpy
+=====================
+
+.. toctree::
+    :maxdepth: 3
+
+    funcs.auto
+    numpy.auto

docs/source/api_doc/numpy/numpy.rstc

+treetensor.numpy.numpy
\ No newline at end of file

docs/source/api_doc/utils/clazz.rstc

+treetensor.utils.clazz
\ No newline at end of file

docs/source/api_doc/utils/func.rstc

+treetensor.utils.func
\ No newline at end of file

docs/source/api_doc/utils/index.rst

+treetensor.utils
+=====================
+
+.. toctree::
+    :maxdepth: 3
+
+    clazz.auto
+    func.auto

docs/source/index.rst

@@ -21,7 +21,9 @@ module.
 
     api_doc/common/index
     api_doc/config/index
+    api_doc/numpy/index
     api_doc/tensor/index
+    api_doc/utils/index
 
 
 .. toctree::