Update GitHub Actions badge

Changed the GitHub Pages Deploy badge and link to reference the correct workflow file: build_documentation.yml instead of mkdocs.yml.

Author: santaimpersonator

README.md

@@ -17,7 +17,7 @@ Documentation
 --------------
 
 - **[Product Manual](http://docs.sparkfun.com/SparkFun_GNSSDO/)** - Product manual for the GNSSDO hosted by GitHub pages.<br>
-  [![Built with Material for MkDocs](https://img.shields.io/badge/Material_for_MkDocs-526CFE?logo=MaterialForMkDocs&logoColor=white)](https://squidfunk.github.io/mkdocs-material/) [![GitHub Pages Deploy](https://github.com/sparkfun/SparkFun_GNSSDO/actions/workflows/mkdocs.yml/badge.svg)](https://github.com/sparkfun/SparkFun_GNSSDO/actions/workflows/mkdocs.yml)
+  [![Built with Material for MkDocs](https://img.shields.io/badge/Material_for_MkDocs-526CFE?logo=MaterialForMkDocs&logoColor=white)](https://squidfunk.github.io/mkdocs-material/) [![GitHub Pages Deploy](https://github.com/sparkfun/SparkFun_GNSSDO/actions/workflows/build_documentation.yml/badge.svg)](https://github.com/sparkfun/SparkFun_GNSSDO/actions/workflows/build_documentation.yml)
 
 
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