Update README with new lazy bgimage feature

Author: westonruter

plugins/image-prioritizer/readme.txt

@@ -15,12 +15,13 @@ This plugin optimizes the loading of images (and videos) with prioritization, la
 
 The current optimizations include:
 
-1. Ensuring `fetchpriority=high` is only added to an `IMG` when it is the Largest Contentful Paint (LCP) element across all responsive breakpoints.
-2. Adding breakpoint-specific `fetchpriority=high` preload links for the LCP elements which are `IMG` elements or elements with a CSS `background-image` inline style.
-3. Applying lazy-loading to `IMG` tags based on whether they appear in any breakpoint’s initial viewport. (Additionally, [`sizes=auto`](https://make.wordpress.org/core/2024/10/18/auto-sizes-for-lazy-loaded-images-in-wordpress-6-7/) is then also correctly applied.)
-4. Adding `fetchpriority=low` to `IMG` tags which appear in the initial viewport but are not visible, such as when they are subsequent carousel slides.
-5. Reducing the size of the `poster` image of a `VIDEO` from full size to the size appropriate for the maximum width of the video (on desktop).
-6. Lazy-loading `VIDEO` tags by setting the appropriate attributes based on whether they appear in the initial viewport. If a `VIDEO` is the LCP element, it gets `preload=auto`; if it is in an initial viewport, the `preload=metadata` default is left; if it is not in an initial viewport, it gets `preload=none`. Lazy-loaded videos also get initial `preload`, `autoplay`, and `poster` attributes restored when the `VIDEO` is going to enter the viewport.
+1. Ensure `fetchpriority=high` is only added to an `IMG` when it is the Largest Contentful Paint (LCP) element across all responsive breakpoints.
+2. Add breakpoint-specific `fetchpriority=high` preload links for the LCP elements which are `IMG` elements or elements with a CSS `background-image` inline style.
+3. Apply lazy-loading to `IMG` tags based on whether they appear in any breakpoint’s initial viewport. (Additionally, [`sizes=auto`](https://make.wordpress.org/core/2024/10/18/auto-sizes-for-lazy-loaded-images-in-wordpress-6-7/) is then also correctly applied.)
+4. Implement lazy-loading of CSS background images added via inline `style` attributes.
+5. Add `fetchpriority=low` to `IMG` tags which appear in the initial viewport but are not visible, such as when they are subsequent carousel slides.
+6. Reduce the size of the `poster` image of a `VIDEO` from full size to the size appropriate for the maximum width of the video (on desktop).
+7. Lazy-load `VIDEO` tags by setting the appropriate attributes based on whether they appear in the initial viewport. If a `VIDEO` is the LCP element, it gets `preload=auto`; if it is in an initial viewport, the `preload=metadata` default is left; if it is not in an initial viewport, it gets `preload=none`. Lazy-loaded videos also get initial `preload`, `autoplay`, and `poster` attributes restored when the `VIDEO` is going to enter the viewport.
 
 **This plugin requires the [Optimization Detective](https://wordpress.org/plugins/optimization-detective/) plugin as a dependency.** Please refer to that plugin for additional background on how this plugin works as well as additional developer options.