Add encyclopedia galactica and README.md

.gitmodules

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+[submodule "encyclopedia_galactica"]
+	path = encyclopedia_galactica
+	url = https://github.com/antsouchlos/EncyclopediaGalactica.git

README.md

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+# CommonSense
+
+A BLE-based PCB for measuring humidity and temperature
+
+## Downloading libraries
+
+After cloning, the libraries have to be downloaded using
+```bash
+$ git submodule update --init
+```