docs: minor grammatical fix (#50)

Author: sreeram-venkitesh

docs/guide/installation.md

@@ -6,7 +6,7 @@ title: 'Installation'
 
 ## Prerequisites
 
-- [**npm**](https://www.npmjs.com/) it is a package manager for the JavaScript programming language.
+- [**npm**](https://www.npmjs.com/) is a package manager for the JavaScript programming language.
 - [**node.js**](https://nodejs.org/en/) is an open-source, cross-platform JavaScript run-time environment that executes JavaScript code outside of a browser.
 - [**git**](https://git-scm.com/) is a version control system for tracking changes in computer files and coordinating work on those files among multiple people. It is primarily used for source code management in software development.