document progress colour

- fixes #2982

Author: casperdcl

docs/source/examples/Widget List.ipynb

@@ -237,6 +237,7 @@
     "    max=10,\n",
     "    description='Loading:',\n",
     "    bar_style='', # 'success', 'info', 'warning', 'danger' or ''\n",
+    "    style={'bar_color': 'maroon'},\n",
     "    orientation='horizontal'\n",
     ")"
    ]
@@ -264,6 +265,7 @@
     "    max=10.0,\n",
     "    description='Loading:',\n",
     "    bar_style='info',\n",
+    "    style={'bar_color': '#ffff00'},\n",
     "    orientation='horizontal'\n",
     ")"
    ]