📝 Clarify justification for moving

build/README.md

@@ -2,8 +2,9 @@
 
 This folder contains the grunt configuration and tasks to build Atom.
 
-It was moved from the root of the repository so that native modules would be
+It was moved from the root of the repository so that any native modules used
-compiled against node's v8 headers instead of Atom's v8 headers.
+would be compiled against node's v8 headers since anything stored in
+`node_modules` at the root of the repo is compiled against atom's v8 headers.
 
 New build dependencies should be added to the `package.json` file located in
 this folder.