Replace occurrences of `MacOS` with `macOS` (#6494)

components/Common/Select/index.stories.tsx

···
           },
           {
             value: 'macos',
-            label: 'MacOS',
+            label: 'macOS',
             iconImage: <Apple width={16} height={16} />,
           },
           {

pages/en/learn/getting-started/how-to-install-nodejs.md

···
 
 Node.js can be installed in different ways. This post highlights the most common and convenient ones. Official packages for all the major platforms are available at [https://nodejs.org/download/](/download).
 
-One very convenient way to install Node.js is through a package manager. In this case, every operating system has its own. Other package managers for MacOS, Linux, and Windows are listed in [https://nodejs.org/download/package-manager/](/download/package-manager/)
+One very convenient way to install Node.js is through a package manager. In this case, every operating system has its own. Other package managers for macOS, Linux, and Windows are listed in [https://nodejs.org/download/package-manager/](/download/package-manager/)
 
 `nvm` is a popular way to run Node.js. It allows you to easily switch the Node.js version, and install new versions to try and easily rollback if something breaks. It is also very useful to test your code with old Node.js versions.
 

util/downloadUtils.ts

···
 // A utility enum to help convert `userOs` data type to user-readable format
 export enum OperatingSystem {
   WIN = 'Windows',
-  MAC = 'MacOS',
+  MAC = 'macOS',
   LINUX = 'Linux',
   OTHER = 'Other',
 }