doc: improve wording in vm.md and esm.md

doc/api/esm.md

@@ -620,8 +620,8 @@ stateless):
 
 ##### Approach #2: Isolate State
 
-The most straightforward `package.json` would be one that defines the separate
-CommonJS and ES module entry points directly:
+A `package.json` file can define the separate CommonJS and ES module entry
+points directly:
 
 <!-- eslint-skip -->
 ```js

doc/api/vm.md

@@ -362,9 +362,8 @@ specification.
 
 Unlike `vm.Script` however, every `vm.Module` object is bound to a context from
 its creation. Operations on `vm.Module` objects are intrinsically asynchronous,
-in contrast with the synchronous nature of `vm.Script` objects. With the help
-of async functions, however, manipulating `vm.Module` objects is fairly
-straightforward.
+in contrast with the synchronous nature of `vm.Script` objects. The use of
+'async' functions can help with manipulating `vm.Module` objects.
 
 Using a `vm.Module` object requires three distinct steps: creation/parsing,
 linking, and evaluation. These three steps are illustrated in the following