Update landing page for NumPy chapter (#79)

* Use pythia-datasets in pandas notebook

* New landing page for numpy chapter

* Update numpy.md

Co-authored-by: Julia Kent <[email protected]>

Author: brian-rose

core/numpy.md

@@ -4,4 +4,12 @@
 This content is under construction!
 ```
 
-This section will contain tutorials on array computing with [NumPy](https://numpy.org).
+This section contains tutorials on array computing with [NumPy](https://numpy.org).
+
+---
+
+From the [NumPy documentation](https://numpy.org/doc/stable/user/whatisnumpy.html):
+
+> NumPy is the fundamental package for scientific computing in Python. It is a Python library that provides a multidimensional array object, various derived objects (such as masked arrays and matrices), and an assortment of routines for fast operations on arrays, including mathematical, logical, shape manipulation, sorting, selecting, I/O, discrete Fourier transforms, basic linear algebra, basic statistical operations, random simulation, and much more.
+
+NumPy's position at the center of the scientific Python ecosystem means that all users should start here in their learning journey through the core scientific packages.