Update documentation (#827)
Update documentation (#827)

Added nextflowVersion documentation
nextflow-io/nextflow,nextflow-io/nextflow,robsyme/nextflow,nextflow-io/nextflow,nextflow-io/nextflow,heuermh/nextflow,heuermh/nextflow,heuermh/nextflow,heuermh/nextflow,nextflow-io/nextflow,robsyme/nextflow,heuermh/nextflow,robsyme/nextflow,robsyme/nextflow,robsyme/nextflow