support pywebio_battery demo in doc

wang0618 · wang0618 · commit 386ab1c57012 · 2022-09-01T21:16:43.000+08:00
diff --git a/demos/doc_demo.py b/demos/doc_demo.py
@@ -15,7 +15,7 @@
 from pywebio.output import *
 from pywebio.session import *
 from pywebio.pin import *
-
+from pywebio_battery import *
 
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