doc: update using_tensorflow topic

doc/conf.py

@@ -60,6 +60,7 @@ def __getattr__(cls, name):
     "sphinx.ext.coverage",
     "sphinx.ext.autosummary",
     "sphinx.ext.napoleon",
+    "sphinx.ext.autosectionlabel"
 ]
 
 # Add any paths that contain templates here, relative to this directory.
@@ -95,3 +96,6 @@ def __getattr__(cls, name):
 
 # autosummary
 autosummary_generate = True
+
+# autosectionlabel
+autosectionlabel_prefix_document = True