Typo correction in msPurityA Offset argument legend 999.5 to 99.5 (#43)

Author: yguitton

tools/msPurity/macros.xml

@@ -23,7 +23,7 @@
     <xml name="offsets">
         <param argument="--minoffset" type="float" label="minoffset" value="0.5"
                help="Offset to the 'left' for the precursor range e.g. if precursor of interest is
-               100.0 then the range would be from 999.5 to 100.0"/>
+               100.0 then the range would be from 99.5 to 100.0"/>
         <param argument="--maxoffset" type="float" label="maxoffset" value="0.5"
                help="Offset to the 'right' for the precursor range  e.g. if precursor of interest is
                100.0 then the range would be from 100.0 to 100.5"/>