Added --no-update hint to composer docs
Use the correct variable as the key into $record

It was using $fieldName, which is the CSV field name, not the database
field name. This prevents duplicate detection from working. It now
properly uses $SQL_fieldName
Merge pull request #1820 from oddnoc/csvbulkloader-findexisting-3.0

Use the correct variable as the key into $record
Merge pull request #1776 from chillu/pulls/composer-require-docs

Added --no-update hint to composer docs