Add SINGULAR to platform tags (PR #686)

SAMv1.tex

@@ -325,7 +325,7 @@ \subsection{The header section}
   & {\tt PG} & Programs used for processing the read group.\\\cline{2-3}
   & {\tt PI} & Predicted median insert size, rounded to the nearest integer.\\\cline{2-3}
   & {\tt PL} & Platform/technology used to produce the reads. \emph{Valid values}:
-  {\tt CAPILLARY}, {\tt DNBSEQ} (MGI/BGI), {\tt ELEMENT}, {\tt HELICOS}, {\tt ILLUMINA}, {\tt IONTORRENT}, {\tt LS454}, {\tt ONT} (Oxford Nanopore), {\tt PACBIO} (Pacific Biosciences), {\tt SOLID}, and {\tt ULTIMA}.
+  {\tt CAPILLARY}, {\tt DNBSEQ} (MGI/BGI), {\tt ELEMENT}, {\tt HELICOS}, {\tt ILLUMINA}, {\tt IONTORRENT}, {\tt LS454}, {\tt ONT} (Oxford Nanopore), {\tt PACBIO} (Pacific Biosciences), {\tt SINGULAR}, {\tt SOLID}, and {\tt ULTIMA}.
   This field should be omitted when the technology is not in this list (though the {\tt PM} field may still be present in this case) or is unknown.\\\cline{2-3}
   & {\tt PM} & Platform model. Free-form text providing further details of the platform/technology used.\\\cline{2-3}
   & {\tt PU} & Platform unit (e.g., flowcell-barcode.lane for Illumina or slide for SOLiD). Unique identifier.\\\cline{2-3}
@@ -1450,6 +1450,7 @@ \section{SAM Version History}\label{sec:history}
 \subsection*{1.6: 28 November 2017 to current}
 
 \begin{itemize}
+\item Add {\tt SINGULAR} to the list of {\tt @RG PL} header tag values. (May 2023)
 \item Clarify that {\tt @RG PI} values are integers. (May 2023)
 \item Add {\tt ELEMENT} and {\tt ULTIMA} to the list of {\tt @RG PL} header tag values. (Aug 2022)
 \item Clarify that header field tags must be distinct within each line, and that the ordering of both header fields and alignment optional fields is not significant. (Jun 2021)