Understanding Scrappy Middleware Configuration

I want to set HTTPCACHE_ENABLED to True in Scrapy, but I don't know how to set it.

I read the Scrapy configuration documentation (https://doc.scrapy.org/en/1.4/topics/downloader-middleware.html), but I don't know how to set HTTPCACHE_ENABLED to True since the following is the only example.

Example)

DOWNLOADER_MIDDLEWARES={
    'myproject.middleware.CustomDownloaderMiddleware':543,
}

• A little deeper explanation
• Configuration Example
• Useful Sites
• Explanation of the original argument

I would appreciate it if you could write it down.