Add Python API docs for test_utils and visualization (apache#12455)

* adding missing python modules as tools folder for docs

* adding missing python modules as tools folder for docs

* adjusted paths after testing build

docs/api/python/index.md

@@ -177,4 +177,14 @@ Code examples are placed throughout the API documentation and these can be run a
    :maxdepth: 1
 
    symbol_in_pictures/symbol_in_pictures.md
-```
+```
+
+## Tools
+
+```eval_rst
+.. toctree::
+    :maxdepth: 1
+
+    tools/test_utils.md
+    tools/visualization.md
+```

docs/api/python/tools/test_utils.md

@@ -0,0 +1,27 @@
+# Test Utilities
+
+This module has a variety of tools that help using and testing MXNet.
+
+```eval_rst
+    .. currentmodule:: mxnet.test_utils
+```
+
+```eval_rst
+.. autosummary::
+    :nosignatures:
+
+    mxnet.test_utils
+```
+
+## API Reference
+
+<script type="text/javascript" src='../../../_static/js/auto_module_index.js'></script>
+
+```eval_rst
+
+.. automodule:: mxnet.test_utils
+    :members:
+
+```
+
+<script>auto_index("api-reference");</script>

docs/api/python/tools/visualization.md

@@ -0,0 +1,27 @@
+# Visualization
+
+This module contains visualization features.
+
+```eval_rst
+    .. currentmodule:: mxnet.visualization
+```
+
+```eval_rst
+.. autosummary::
+    :nosignatures:
+
+    mxnet.visualization
+```
+
+## API Reference
+
+<script type="text/javascript" src='../../../_static/js/auto_module_index.js'></script>
+
+```eval_rst
+
+.. automodule:: mxnet.visualization
+    :members:
+
+```
+
+<script>auto_index("api-reference");</script>