update rewrite-url docs for stylelint config

* Use languageOptions instead of overriding declaration-property-value-no-unknown rule config
* Make syntax consistent with JSON config: Only use double quotes, no trailing commas

Author: Emanuel Hoogeveen

plugins/postcss-rewrite-url/README.md

@@ -142,20 +142,21 @@ Stylelint is able to check for unknown property values.
 Setting the correct configuration for this rule makes it possible to check even non-standard syntax.
 
 ```js
-	'declaration-property-value-no-unknown': [
-		true,
-		{
-			"typesSyntax": {
-				"url": "| rewrite-url( <string> <url-modifier>* )"
-			}
-		},
-	],
-	'function-no-unknown': [
+"languageOptions": {
+	"syntax": {
+		"types": {
+			"url": "| rewrite-url( <string> <url-modifier>* )"
+		}
+	}
+},
+"rules": {
+	"function-no-unknown": [
 		true,
 		{
 			"ignoreFunctions": ["rewrite-url"]
 		}
-	],
+	]
+}
 ```
 
 [cli-url]: https://github.com/csstools/postcss-plugins/actions/workflows/test.yml?query=workflow/test

plugins/postcss-rewrite-url/docs/README.md

@@ -109,20 +109,21 @@ Stylelint is able to check for unknown property values.
 Setting the correct configuration for this rule makes it possible to check even non-standard syntax.
 
 ```js
-	'declaration-property-value-no-unknown': [
-		true,
-		{
-			"typesSyntax": {
-				"url": "| rewrite-url( <string> <url-modifier>* )"
-			}
-		},
-	],
-	'function-no-unknown': [
+"languageOptions": {
+	"syntax": {
+		"types": {
+			"url": "| rewrite-url( <string> <url-modifier>* )"
+		}
+	}
+},
+"rules": {
+	"function-no-unknown": [
 		true,
 		{
 			"ignoreFunctions": ["rewrite-url"]
 		}
-	],
+	]
+}
 ```
 
 <linkList>