Added ChEBI for 5caU modification

Author: jkbonfield

SAMtags.tex

@@ -515,7 +515,7 @@ \subsection{Base modifications}
 \hline
 T & g & 5hmU  & 5-Hydroxymethyluracil   & 16964 \\
 T & e & 5fU   & 5-Formyluracil          & 80961 \\
-T & b & 5caU  & 5-Carboxyluracil        & ? \\
+T & b & 5caU  & 5-Carboxyluracil        & 17477 \\
 \hline
 A & a & 6mA   & 6-Methyladenine         & 28871 \\
 \hline