alert users about slight change in numbers

NEWS.md

@@ -1,7 +1,7 @@
 # volcalc (development version)
 
 * Added a `validate = TRUE` option to `calc_vol()` and `get_fx_groups()` that returns `NA`s when there are suspected errors in parsing SMILES or .mol files. This is unfortunately not available on Windows due to differences in the windows version of `ChemmineOB`
-* Users can now supply a temperature at which to calculate volatility estimates.
+* Users can now supply a temperature at which to calculate volatility estimates. As a result, RVI values may now be *slightly* different compared to those from `volcalc` v2.1.2 due to rounding differences.
 * Inputs to `calc_vol()` supplied as a named vector of SMILES strings now properly pass the names to `ChemmineR::smile2sdf()` where they are used as the molecule name.
 
 # volcalc 2.1.2