Clarify metadata need in Script_VOCAL_unified.R

[huguesrichard]

This issue is related to #10 and comes from the fact that by default the VOCAL alert throwing phase doesn't need a metadata file to run. However the metadata data file in expected to contain the following columns (default name in parenthesis):

• sample ID (ID)
• Lineage information (LINEAGE)
• Geolocalisation data (PRIMARY_DIAGNOSTIC_LAB_PLZ)
• date (SAMPLING_DATE)

In particular the lineage information in important to be able to identify previous Variants of Concern and throw pink alert.

Step to be taken:

• Update the documentation to explain that
• Provide an option in the nextflow workflow