Documentation for `_set_trace_grid_reference` from plotly.subplots.py mentions `plotly.subplots.make_subplot`, which does not exist

Line 1336 from plotly.subplots.py reads
```
See the docstring for the specs argument to plotly.subplots.make_subplot 
```

Minor issue, but this is meant to be `plotly.subplots.make_subplots` (with an `s` at the end). I was rather confused when I got the above message in an error, typed `help(plotly.subplots.make_subplot)`, only to be told it doesn't exist