Add links to NGSI-LD API specification

Author: jason-fox

README.ja.md

@@ -1,4 +1,4 @@
-# Getting Started[<img src="https://img.shields.io/badge/NGSI-LD-d6604d.svg" width="90"  align="left" />](https://www.etsi.org/deliver/etsi_gs/CIM/001_099/009/01.08.01_60/gs_cim009v010801p.pdf)[<img src="https://fiware.github.io/tutorials.Getting-Started/img/Fiware.png" align="left" width="162">](https://www.fiware.org/)<br/>
+# Getting Started[<img src="https://img.shields.io/badge/NGSI-LD-d6604d.svg" width="90"  align="left" />](https://cim.etsi.org/NGSI-LD/official/0--1.html)[<img src="https://fiware.github.io/tutorials.Getting-Started/img/Fiware.png" align="left" width="162">](https://www.fiware.org/)<br/>
 
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