add examples for usage of \unit{}

Author: nuest

inst/rmarkdown/templates/copernicus_article/skeleton/skeleton.Rmd

@@ -310,7 +310,7 @@ Publi \leftrightarrow cations
 
 ## PHYSICAL UNITS
 
-Please use `\unit{}` and apply the exponential notation
+Please use `\unit{}` (allows to save the math/`$` environment) and apply the exponential notation, for example \( 3.14\,\unit{km\,h^{-1}} \) (using LaTeX mode: `\( 3.14\,\unit{...} \)`) or \unit{0.872\,m\,s^{-1}} (using only `\unit{0.872\,m\,s^{-1}}`).
 
 \conclusions