DOC: plot doesn't show in some environments
### 

- [X] I have checked that the issue still exists on the latest versions of the docs on `master` [here](https://pandas.pydata.org/docs/dev/)


### Location of the documentation

https://pandas.pydata.org/docs/dev/user_guide/10min.html#plotting

### Documentation problem

When following the tutorial, plot may not appear, depending on the environment.  Some environments require `plot.show`, some will require `plot.savefig`.
PR #43544 adds a very brief explanation.

### Suggested fix for documentation

If running under Jupyter Notebook, the plot will appear on `~ts.plot`.  Otherwise use [`matplotlib.pyplot.show`](https://matplotlib.org/3.1.1/api/_as_gen/matplotlib.pyplot.show.html) to show it or [`matplotlib.pyplot.savefig`](https://matplotlib.org/3.1.1/api/_as_gen/matplotlib.pyplot.savefig.html) to write it to a file.

   plt.show();
