Update janno file requirements to include Poseidon_ID

Added 'Poseidon_ID' to the list of required columns in the janno file.

Author: TCLamnidis

minotaur.md

@@ -103,6 +103,7 @@ The `Poseidon_ID` column of the prepared janno should match those specified in t
 
 The prepared janno file should include information for as many of the following columns as possible:
 
+- Poseidon_ID
 - Genetic_Sex
 - Group_Name
 - Alternative_IDs