Add explanation for why modern format images may not appear after upload

[b1ink0]

Users frequently open support topics confused about why their uploads aren't generating AVIF/WebP files, or why images on the frontend are still JPEG.

In most cases this is expected, the plugin discards the converted file if it's larger than the original (controlled by webp_uploads_discard_larger_generated_images, which defaults to true). But there's currently nothing in the admin dashboard that explains this.

It would help to surface some explanation somewhere in the settings so users understand the default behavior.

Relevant support topics:

• https://wordpress.org/support/topic/the-converted-files-are-not-displayed/
• https://wordpress.org/support/topic/webp-not-generated-served-when-output-fallback-images-is-enabled/

Related: #2390, #1836

[westonruter]

Yes, it makes sense to include it somewhere here:

[westonruter]

It would also make sense to include in the README's FAQ. Nevertheless, is this not already present?

performance/plugins/webp-uploads/readme.txt

Lines 55 to 64 in 61b1379

	= I've activated the Modern Image Formats plugin, but WebP images are not always generated when I upload a JPEG image. Why? =
	There are two primary reasons that a WebP image may not be generated:
	1. The Modern Image Formats plugin has identified that the WebP version of the uploaded JPEG image would have a larger file size than the original JPEG image, so it does not generate the WebP version.
	2. The JPEG image was not uploaded to the [Media Library](https://wordpress.com/support/media/). At this time, WebP versions are only generated for images to the Media Library. WebP versions are not generated for JPEG images that are added to your site in other ways, such as in a template file or the [Customizer](https://wordpress.com/support/customizer/).
	= With the Modern Image Formats plugin activated, will the plugin generate JPEG and WebP versions of every image that I upload? =
	By default, the Modern Image Formats plugin will only generate WebP versions of the images that you upload. If you wish to have both WebP **and** JPEG versions generated, you can navigate to **Settings > Media** and enable the **Generate JPEG files in addition to WebP** option.

[b1ink0]

Looks like this is already present in the FAQ. Wouldn’t it make sense to link to the FAQ from the admin dashboard settings then?

[westonruter]

Yeah, good idea. That would reduce duplcation.