Added a more descriptive explanation as to what npm does, and what de…

…pendencies are, including punctuation.

apps/site/pages/en/learn/getting-started/an-introduction-to-the-npm-package-manager.md

@@ -18,7 +18,7 @@ It started as a way to download and manage dependencies of Node.js packages, but
 
 ## Packages
 
-`npm` installs, updates and manages downloads of dependencies of your project. Dependencies are pre-written pieces of code such as libraries and packages that your Node.js application needs to work.  
+`npm` installs, updates and manages downloads of dependencies of your project. Dependencies are pre-built pieces of code, such as libraries and packages, that your Node.js application needs to work.  
 
 ### Installing all dependencies