title: plotly make_subplots how to use specs parameter
body: <p>I am trying to create a figure with 2 subplots (rows=2,cols=1)
  Out of these, i want the first subplot which will be the first row plot to have secondary_y = True spec.
  And the 2nd row plot need not have any secondary_y requirement.
  Can you confirm how i can use this specs argument ? I have looked at the <a href="https://plotly.com/python-api-reference/generated/plotly.subplots.make_subplots.html" rel="nofollow noreferrer">https://plotly.com/python-api-reference/generated/plotly.subplots.make_subplots.html</a> documentation, however i think i dont really understand it fully.</p>
  <p>Error:</p>
  <pre><code>ValueError: 
  The 'specs' argument to make_subplots must be a 2D list of dictionaries with dimensions (2 x 1).
      Received value of type &lt;class 'list'&gt;: [[{'secondary_y': True}], [{}, {}]]
  </code></pre>
  <p>Can you assist how this would be ?</p>
  <pre><code>fig = make_subplots(rows=2,cols=1,
                      shared_xaxes = True,vertical_spacing = 0.02,
                      specs=[[{&quot;secondary_y&quot;: True}], 
                             [{},{}]
                            ]
                      )
  
  fig.add_trace(go.Scatter(x=df['timestamp_gmt'],y=df['mid'],opacity=0.8,
                            name = &quot;Price&quot;),secondary_y=True,row=1,col=1)
  fig.add_trace(go.Scatter(x=df2['date'],y=df2['cnd'],mode='markers',
                            name=&quot;abc&quot;),secondary_y=False,row=1,col=1)
  if xlist:
      fig.add_annotation(x=xlist[0],y=df2['cnd'].max(),
          text=&quot;Arrow text&quot;, showarrow=True,arrowhead=2,row=1,col=1)
      if len(xlist) &gt; 1 :
          for x in xlist:
              fig.add_vline(x=x, line_width=0.8,opacity = 0.55,row=1,col=1)
      else:
          fig.add_vline(x=xlist[0],line_width=0.8,opacity=0.55,row=1,col=1)
  
  
  fig.update_layout(margin=dict(l=30, r=1, t=20, b=20))    
  fig.update_layout(legend=dict(    yanchor=&quot;top&quot;,    y=0.99,    xanchor=&quot;right&quot;,    x=0.90    ))
  fig.update_yaxes(tickprefix=&quot;$&quot;)
  
  fig.add_trace(go.Scatter(x=df2_gpby['date'],y=df2_gpby[variable_col],opacity=0.8,
                            name = &quot;Price&quot;),secondary_y=False,row=2,col=1)
  
  
  fig.update_xaxes(matches=None, showticklabels=True, visible=True)
  fig.update_layout(margin=dict(l=30, r=85, t=30, b=20))
  fig.update_layout(legend=dict(    yanchor=&quot;top&quot;,    y=0.99,    xanchor=&quot;right&quot;,    x=0.99    ))
  fig.update_layout(template='plotly_white')
  </code></pre>