docs: change i.e. to e.g. in search placeholder (#6142)

**What's the problem this PR addresses?**

In the website search placeholder text (something like `Search packages
(i.e. babel, webpack, react, ...)`), the word "i.e." is used
incorrectly. ["i.e." means "that
is,"](https://en.wiktionary.org/wiki/i.e.#Usage_notes) but the intended
meaning here is ["e.g.," meaning "for
example."](https://en.wiktionary.org/wiki/e.g.)

**How did you fix it?**

Changed the three instances I found of this placeholder text to use
"e.g." instead.

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~👆 Not sure how to do that / if it's applicable to docs-only changes.~
never mind, see
[comment](#6142 (comment))
below.
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Author: pwbriggs

packages/docusaurus/src/pages/index.tsx

@@ -69,7 +69,7 @@ export default function Home(): JSX.Element {
                 </div>
               </h1>
               <p>Yarn is a package manager that doubles down as project manager. Whether you work on simple projects or industry monorepos, whether you're an open source developer or an enterprise user, Yarn has your back.</p>
-              <input className={styles.search} placeholder={`Search packages (i.e. babel, webpack, react, ...)`} autoFocus={true} onChange={handleChange}/>
+              <input className={styles.search} placeholder={`Search packages (e.g. babel, webpack, react, ...)`} autoFocus={true} onChange={handleChange}/>
               <div className={styles.info}>
                 This documentation covers Yarn 4+. For the previous documentation dedicated to 3.6 and below, please refer to <a href={`https://v3.yarnpkg.com/`}>v3.yarnpkg.com</a>.
               </div>

packages/docusaurus/src/pages/search.tsx

@@ -145,7 +145,7 @@ function SearchBar() {
   };
 
   return (
-    <input className={clsx(indexStyles.search, styles.search)} autoFocus={true} placeholder={`Search packages (i.e. babel, webpack, react, ...)`} value={query} onChange={handleChange}/>
+    <input className={clsx(indexStyles.search, styles.search)} autoFocus={true} placeholder={`Search packages (e.g. babel, webpack, react, ...)`} value={query} onChange={handleChange}/>
   );
 }