Add Missing data issue template

.github/ISSUE_TEMPLATE/missing-data.md

@@ -0,0 +1,18 @@
+---
+name: Missing Data
+about: Report data which needs to be added to the database
+title: 'Data ingest request from: <publication>'''
+labels: data ingestion
+assignees: ''
+
+---
+
+Please provide as much information as possible about the data you think should be added. 
+
+# Source/survey/catalogue name(s)
+
+# SIMBAD/CDS/Vizier link to data source(s), if available
+
+# What data needs to be added?
+
+# Reference(s) paper for the data