Example interfacing GEE with contextily

[darribas]

First stub, unfinished. Eventually, this PR will contain:

• Notebook with example linking contextily to GEE (elevation model and Sentinel 2 Landsat 8)
• Hook to display the notebook on the website

Also, with this, we'd be starting the series of interfacing contextily with other packages. My suggestion here is to use the name of the notebook friends_XXX.ipynb where XXX is the package we show how to interface. So, for example, we could also have friends_cenpy.ipynb, friends_osmnx.ipynb, etc. These should also display ideally under a horizontal bar on the side menu of the website (would this be possible @jorisvandenbossche?).

Will confirm when this can be reviewed/merged.

[ljwolf]

We could throw a basemap on this?

[darribas]

OK I think the GEE is ready to go, at least for now. I've added it as a separate notebook but not separate (not sure how to do that)

[jorisvandenbossche]

To just add it to the sidebar on the doc site for now, you need to update:

• https://github.com/geopandas/contextily/blob/master/docs/index.rst -> add it to the toctree

• contextily/docs/conf.py

  Lines 81 to 89 in 97d5f04

  	files_to_copy = [
  	"notebooks/add_basemap_deepdive.ipynb",
  	"notebooks/intro_guide.ipynb",
  	"notebooks/places_guide.ipynb",
  	"notebooks/providers_deepdive.ipynb",
  	"notebooks/warping_guide.ipynb",
  	"notebooks/working_with_local_files.ipynb",
  	"tiles.png"
  	]

  -> add it to this list of files to copy

[darribas]

Added! This is ready for review.