added link to image to show colormap example (#189)

* updated workflow in cost overlay sample notebook.

* added code decoration in the Invoking Raster Analysis in Portal.

* simplified code for `raster.functions` with modified import, added map algebra, edited intro, output names, and other text.

* fixed typos in intro paragraph.

* added img to display 1-9 colormap example

Author: jyaistMap

samples/04_gis_analysts_data_scientists/calculating_cost_surfaces_using_weighted_overlay_analysis.ipynb

@@ -477,7 +477,7 @@
     "\n",
     "In this step we use the Remap function to normalize the input datasets to a common scale of 1 - 9. Locations assigned the value of 1 are considered the least suitable according to our criteria (e.g. the steepest slopes are the least accessible for travel), while locations assigned the value of 9 are considered the most suitable according to our criteria (e.g. areas that are least modified by human activity are more \"natural\").\n",
     "\n",
-    "![title](images/colormap.png)"
+    "![title](http://esri.github.io/arcgis-python-api/notebooks/nbimages/04_WeightedOverlay_clrmp.png)"
    ]
   },
   {