Update document, add a colab example for reading data, upgrade numpy dependency (#34)

* Minor update to docs

* WIP

* adjust numpy requirement

* prepare example for reading data from SN dataset

* prepare example for reading data from SN dataset

* clean

documentation/README.md

@@ -1,9 +1,11 @@
-This folder contains files for the documentation: [https://scenarionet.readthedocs.io/](https://scenarionet.readthedocs.io/).
+This folder contains files for the documentation:
+[https://scenarionet.readthedocs.io/](https://scenarionet.readthedocs.io/).
 
-To build documents locally, please run the following codes:
+To build documents locally, please run the following script:
 
-```
+```bash
+cd scenarionet
 pip install -e .[doc]
-cd scenarionet/documentation
+cd documentation
 make html
 ```