replace erg/s with m/s in VOUnits example

As agreed following comment by Tom.

VOTable.tex

@@ -1148,7 +1148,7 @@ \subsection{Units}
 and exponentiation by the symbol ``{\tt**}''.
 Examples are \attrval{unit}{m**2} for m$^2$,
 \attrval{unit}{cm**-2.s**-1.keV**-1} for cm$^{-2}$s$^{-1}$keV$^{-1}$,
-or \attrval{unit}{erg/s} for erg\,s$^{-1}$.
+or \attrval{unit}{m/s} for m\,s$^{-1}$.
 
 \subsection{Unified Content Descriptors}
 \label{sec:ucd}