Fix layout of spectrum_demo.py

[vollbier]

Fixes eighth entry in issue #7956

[anntzer]

• Any reason why you swapped the angle and phase plots?
• I would remove the $t$ and $s(t)$ unless you want to add similar labels for all subplots.

[phobson]

I see what you're doing here. But I think we should strive for consistency in the examples/gallery.

In my mind that means, for a single axes object:

fig, ax = plt.subplots()

And for multiples axes:

fig, axes = plt.subplots(ncols=C, nrows=R)

[phobson]

perhaps move this to the end.

[vollbier]

Good points - fixed them.

[vollbier]

@anntzer I swapped the plots around for aesthetic reasons: The minus signs in the y-axis changes the position of the y-labels. $t$ and $s(t)$ are removed.
Furthermore, I would argue that for a correct energy the scaling of the spectrum is of by a factor of 1/Fs or so. I'll investigate that a bit more and put that into a different pull request.

[tacaswell]

might be worth giving them titles / axis labels?

[phobson]

@vollbier sorry to move the goal post on you.

In addition to Tom's request could you:

1. make the figure bigger (add figsize=(7, 7) to the call to subplots)
   2) make the Magnitude y-axis log-scaled (if that's appropriate for the domain)

[vollbier]

I added titles, but I think it's worthwhile leaving the default axis labels, since it's feature of the spectrum functions.

[phobson]

@vollbier sorry to move the goal post on you.

In addition to Tom's request could you:

1. make the figure bigger (add figsize=(7, 7) to the call to subplots)
   2) make the Magnitude y-axis log-scaled (if that's appropriate for the domain)

[NelleV]

Thanks @vollbier ! This is so much better!