Adds import statement to code usage example

[bacoords]

What?

This is a minor documentation change to add the import statement to the code example. This seems to be a consistent pattern. Examples from other packages:

• https://developer.wordpress.org/block-editor/reference-guides/packages/packages-i18n/
• https://developer.wordpress.org/block-editor/reference-guides/packages/packages-autop/

Why?

Added for consistency and because import statements in the example code can be helpful for newer developers.

[github-actions]

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Co-authored-by: bacoords <bacoords@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>

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[t-hamano]

Nice catch 👍

[t-hamano]

This documentation is auto-generated from JSDoc. Therefore, you need to update the following locations:

gutenberg/packages/html-entities/src/index.js

Lines 9 to 14 in 593fd64

	* @example
	* ```js
	* const result = decodeEntities( 'á' );
	* console.log( result ); // result will be "á"
	* ```
	*

Then run docs:build to regenerate the documentation. It's also a good idea to use single quotes instead of double quotes.

[bacoords]

Makes sense about the auto-generation. Thanks @t-hamano for explaining how to commit here- I've pushed an update.

[t-hamano]

LGTM! I'm a little concerned that the GitHub action related to backporting PHP is failing, but this PR does not make any changes to PHP files, and this GitHub action is optional. Therefore, I will merge this PR 👍