docs: use lower-case npm

https://github.com/npm/cli/tree/v8.17.0#faq-on-branding

`npm` should never be capitalized unless it is being displayed in a location that is customarily all-capitals (ex. titles on `man` pages).

pnpm seems to prefer lower-case branding too.

Author: haoqunjiang

README.md

@@ -6,13 +6,13 @@ Utility to setup ESLint in Vue.js projects.
 
 Run the following command in your project root:
 
-With NPM:
+With npm:
 
 ```sh
 npm create @vue/eslint-config@latest
 ```
 
-With PNPM:
+With pnpm:
 
 ```sh
 pnpm create @vue/eslint-config