Add link to Pangeo on landing page (#243)

* Tweak formatting and file names

* Strip notebook output

* Add Pythia+Pangeo info to landing page

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Fix merge glitch

* Fix internal link

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: brian-rose

images/logos/ProjectPythia_Logo_Final-01-Blue.svg

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+# Pythia Foundations
+
+## A community learning resource for Python-based computing in the geosciences
+
+<img src="images/pretty-earth.png" alt="Pretty Earth" width="600px">
+
+This collection covers the foundational skills everyone needs to get started with scientific computing in the open-source Python ecosystem.
+
+<img src="images/logos/ProjectPythia_Logo_Final-01-Blue.svg" alt="Project Pythia logo" height="80px"> _Brought to you by [Project Pythia](https://projectpythia.org), the education working group for [Pangeo](https://pangeo.io)_ <img src="https://raw.githubusercontent.com/pangeo-data/pangeo/master/docs/_static/small_e_logo_cropped.png" alt="Pangeo logo" height="80px">