Add docs page with external resources (#710)

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Author: kylebarron

docs/external-resources.md

@@ -0,0 +1,6 @@
+# External Resources & Examples
+
+A collection of external blog posts discussing Lonboard.
+
+- [**Exploring Mobile Air Quality Data with Lonboard**](https://openaq.medium.com/exploring-mobile-air-quality-data-with-lonboard-af0b99a25eb4) by [OpenAQ](https://openaq.org/).
+- [**Nigeria Geodata**](https://www.linkedin.com/posts/adedoyin-samuel-ajeyomi_grid3-lonboard-nigeria-activity-7235765078925422592-qq7X?utm_source=share&utm_medium=member_desktop) by Adedoyin (Samuel) Ajeyomi and Emmanuel Jolaiya.

mkdocs.yml

@@ -94,6 +94,7 @@ nav:
       - ecosystem/jupyter-widgets.md
       - ecosystem/panel.md
       - ecosystem/shiny.md
+  - external-resources.md
   - Performance: performance.md
   - troubleshooting.md
   - Changelog: CHANGELOG.md