Update high-level docs example

docs/getting_started.rst

@@ -37,20 +37,18 @@ To make a sky image with the `hips` package, follow the following three steps:
 
 
 3. Call the `~hips.make_sky_image` function to fetch the HiPS data
-   and draw it, returning the sky image pixel data as a Numpy array::
+   and draw it, returning the an object of `~hips.HipsDrawResult`::
 
     from hips import make_sky_image
 
-    data = make_sky_image(geometry, hips_survey, 'fits')
+    result = make_sky_image(geometry, hips_survey, 'fits')
 
 
 That's it. Go ahead and try it out for your favourite sky region and survey.
 
 Now you can then save the sky image to local disk e.g. FITS file format::
 
-    from astropy.io import fits
-    hdu = fits.PrimaryHDU(data=data, header=geometry.fits_header)
-    hdu.writeto('my_image.fits')
+    result.write_image('my_image.fits')
 
 or plot and analyse the sky image however you like.
 

hips/draw/simple.py

@@ -219,7 +219,7 @@ def write_image(self, filename: str) -> None:
             Filename
         """
         if self.tile_format == 'fits':
-            hdu = fits.PrimaryHDU(self.image)
+            hdu = fits.PrimaryHDU(data=self.image, header=self.geometry.fits_header)
             hdu.writeto(filename)
         else:
             image = Image.fromarray(self.image)