Add comment to explain use of query values

src/main/groovy/life/qbic/variantstore/database/MariaDBVariantstoreStorage.groovy

@@ -2026,6 +2026,7 @@ gene.id = consequence_has_gene.gene_id INNER JOIN consequence on consequence_has
         sql.withBatch("insert INTO gene (symbol, name, biotype, chr, start, end, synonyms, geneid, description, strand, version) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?) ON DUPLICATE KEY UPDATE symbol=?, name=?, biotype=?, chr=?, start=?, end=?, synonyms=?, geneid=?, description=?, strand=?, version=?") {
             BatchingPreparedStatementWrapper ps ->
             genes.each { gene ->
+                // we have to specify the values twice since we need them for the insert and "on duplicate" part of the sql query
                 ps.addBatch([gene.symbol, gene.name, gene.bioType, gene.chromosome, gene.geneStart,
                              gene.geneEnd, gene.synonyms[0], gene.geneId, gene.description, gene.strand, gene.version,
                              gene.symbol, gene.name, gene.bioType, gene.chromosome, gene.geneStart,