Drop in Unidata datetime intro materials notebook

_toc.yml

@@ -42,6 +42,8 @@
       sections:
         - file: core/cartopy/01_Cartopy_Intro
     - file: core/datetime
+      sections:
+        - file: core/datetime/datetime
     - file: core/pandas
       sections:
         - file: core/pandas/pandas_fullNotebook

core/datetime.md

@@ -4,4 +4,11 @@
 This content is under construction!
 ```
 
-This section will contain tutorials on dealing with times and calendars in scientific Python, including use of the [datetime](https://docs.python.org/3/library/datetime.html) library.
+This section contains tutorials on dealing with times and calendars in scientific Python, beginning with use of the [datetime](https://docs.python.org/3/library/datetime.html) standard library.
+
+When this chapter is fully built out, it will include a comprehensive guide to different time libraries and when/where to use them, including
+
+- [Numpy `datetime64`](https://numpy.org/doc/stable/reference/arrays.datetime.html) for efficient vectorized datetime operations
+- [cftime library](https://unidata.github.io/cftime/) for dealing with non-standard calendars
+
+These will be cross-referenced with tutorials on dealing with timeseries data in [Pandas](pandas) and [Xarray](xarray).