Update source_from_images.ipynb

Make the plot function actually use its input. It only worked by accident.

Untested; edited from github. Living on the edge

docs/source/5_liners/source_from_images.ipynb

@@ -55,11 +55,11 @@
     "    plt.figure(figsize=(12, 5))\n",
     "    plt.subplot(121)\n",
     "    wave = range(3000, 25000)\n",
-    "    plt.plot(wave, image_source.spectra[0](wave))\n",
+    "    plt.plot(wave, src.spectra[0](wave))\n",
     "    plt.xlabel(\"Wavelength [Angstrom]\")\n",
     "    plt.ylabel(\"Flux [ph/s/cm2/Angstrom]\")\n",
     "    plt.subplot(122)\n",
-    "    plt.imshow(image_source.fields[0].data)"
+    "    plt.imshow(src.fields[0].data)"
    ]
   },
   {