Add an example notebook using apply_ufunc to vectorize 1D functions (#3629)

* apply_ufunc vectorize 1D function example

* Small udpates.

* Review + strip output.

* Minor updates.

Author: dcherian

ci/requirements/doc.yml

@@ -14,6 +14,7 @@ dependencies:
   - jupyter_client
   - nbsphinx
   - netcdf4
+  - numba
   - numpy
   - numpydoc
   - pandas<0.25  # Hack around https://github.com/pydata/xarray/issues/3369

doc/examples.rst

@@ -10,3 +10,10 @@ Examples
     examples/visualization_gallery
     examples/ROMS_ocean_model
     examples/ERA5-GRIB-example
+
+Using apply_ufunc
+------------------
+.. toctree::
+    :maxdepth: 2
+
+    examples/apply_ufunc_vectorize_1d