Update mapping.md

Fix the list of aligners names to match the mapping.scala class code

docs/pipelines/mapping.md

@@ -49,7 +49,7 @@ All other values should be provided in the config. Specific config values toward
 | ---- | ---- | -------- |
 | output_dir | Path (**required**) | directory for output files |
 | reference_fasta | Path (**required**) | Path to indexed fasta file to be used as reference |
-| aligner | String (optional) | Which aligner to use. Defaults to `bwa`. Choose from [`bwa`, `bwa-aln`, `bowtie`, `gsnap`, `tophat`, `stampy`, `star`, `star-2pass`, `hisat2`] |
+| aligner | String (optional) | Which aligner to use. Defaults to `bwa`. Choose from [`bwa-mem`, `bwa-aln`, `bowtie`, `bowtie2`, `gsnap`, `tophat`, `stampy`, `star`, `star-2pass`, `hisat2`] |
 | skip_flexiprep | Boolean (optional) | Whether to skip the flexiprep QC step (default = False) |
 | skip_markduplicates | Boolean (optional) | Whether to skip the Picard Markduplicates step (default = False) |
 | skip_metrics | Boolean (optional) | Whether to skip the metrics gathering step (default = False) |