docs: update README.md

Author: marissahuysentruyt

plugins/postcss-rgb-mapping/README.md

@@ -1,6 +1,7 @@
 # postcss-rgb-mapping
 
 > Remaps rgb(a) values to an `rgb` postfixed variable. If an opacity is found, creates a separate `opacity` postfixed variable.
+> Also remaps values that reference a transparent token (for example, `transparent-black-300`) to `rgb` and `opacity` postfixed variables.
 
 ## Installation
 
@@ -17,6 +18,15 @@ This plugin turns this:
 .spectrum--lightest {
 	--spectrum-seafoam-100: rgba(206, 247, 243);
 	--spectrum-seafoam-200: rgba(170, 241, 234, 0.5);
+	--spectrum-transparent-white-100-rgb: 100, 100, 100;
+	--spectrum-transparent-white-100-opacity: 0.5;
+	--spectrum-transparent-white-100: rgba(
+		var(--spectrum-transparent-white-100-rgb),
+		var(--spectrum-transparent-white-100-opacity)
+	);
+	--disabled-static-white-background-color: var(
+		--spectrum-transparent-white-100
+	);
 }
 ```
 
@@ -32,5 +42,21 @@ Into this:
 		var(--spectrum-seafoam-200-rgb),
 		var(--spectrum-seafoam-200-opacity)
 	);
+	--spectrum-transparent-white-100-rgb: 100, 100, 100;
+	--spectrum-transparent-white-100-opacity: 0.5;
+	--spectrum-transparent-white-100: rgba(
+		var(--spectrum-transparent-white-100-rgb),
+		var(--spectrum-transparent-white-100-opacity)
+	);
+	--disabled-static-white-background-color-rgb: var(
+		--spectrum-transparent-white-100-rgb
+	);
+	--disabled-static-white-background-color-opacity: var(
+		--spectrum-transparent-white-100-opacity
+	);
+	--disabled-static-white-background-color: rgba(
+		var(--disabled-static-white-background-color-rgb),
+		var(--disabled-static-white-background-color-opacity)
+	);
 }
 ```