docs: Add a note about CSS Logical 1

Backports I827f90b451cecbb82a777d52f90ba3a9c44b65d9 to the PHP side.

Change-Id: Icae21fafc561aada6f230833c06f15a7c775cff8

Author: ebraminio

README.md

@@ -38,6 +38,14 @@ If a rule is not meant to be flipped by CSSJanus, use a `/* @noflip */` comment
 }
 ```
 
+## CSS Logical Properties
+
+We encourage and recommend use of [CSS logical properties](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_logical_properties_and_values) for the subset of CSS features where a native direction-aware version of a CSS property exists (be sure to check [browser support](https://caniuse.com/)
+for specific properties).
+You can, for example, set properties like `margin-inline-start` instead of `margin-left`, which the browser flips based on content direction, and work seamlessly alongside other CSS properties that CSSJanus flips instead.
+
+Note that CSS logical properties flip based on nearest content direction and content language, whereas CSSJanus is generally configured to flip by user language and UI direction.
+
 ## Port
 
 This is a PHP port of the Node.js implementation of CSSJanus. Feature requests and bugs related