fix: documentation

README.md

@@ -15,10 +15,10 @@ They are sorted in various categories:
 - xyObject: functions that apply on an array of point `[{x,y}]`
 - xreim: functions that apply on an object `{x: [], re:[], im:[]}`
 - reim: functions that apply on an object `{re: [], im:[]}`
+- zone: functions that apply on a zone `{from,to}`
 - zones: functions that apply on an array of zone `[{from,to}]`
 
-The name of the functions starts with the first argument on which they apply.
-
+The name of the functions start with the first argument on which they apply.
 ## Installation
 
 `$ npm i ml-spectra-processing`