docs: update npm install docs URL in Readme.md (#7159)

The link for the npm install command pointed to the old/broken URL path (/getting-started/installing-npm-packages-locally). Updated to the current correct URL (/downloading-and-installing-packages-locally).

Author: Vansh1811

Readme.md

@@ -57,7 +57,7 @@ If this is a brand new project, make sure to create a `package.json` first with
 the [`npm init` command](https://docs.npmjs.com/creating-a-package-json-file).
 
 Installation is done using the
-[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally):
+[`npm install` command](https://docs.npmjs.com/downloading-and-installing-packages-locally):
 
 ```bash
 npm install express