Fix URL in Documentation badge (#25)

* Update README.md

* Update README.md

* Update README.md

added command for adding DB user 'ngb' to the superuser list

* Update README.md

* Fixed URL in documentation badge

README.md

@@ -5,7 +5,7 @@
 [![Docker](https://img.shields.io/docker/pulls/scorpiobroker/scorpio.svg)](https://hub.docker.com/r/scorpiobroker/scorpio/)
 [![fiware](https://nexus.lab.fiware.org/repository/raw/public/badges/stackoverflow/fiware.svg)](https://stackoverflow.com/questions/tagged/fiware)
 <br>
-[![Documentation badge](https://img.shields.io/readthedocs/scorpio.svg)](http://https://scorpio.readthedocs.io//en/latest/?badge=latest)
+[![Documentation badge](https://img.shields.io/readthedocs/scorpio.svg)](https://scorpio.readthedocs.io/en/latest/?badge=latest)
 ![Status](https://nexus.lab.fiware.org/static/badges/statuses/incubating.svg)
 
 Scorpio is an NGSI-LD compliant context broker developed by NEC Laboratories Europe and NEC Technologies India.