Fix API example code in readme.md (#33)

readme.md

@@ -29,21 +29,21 @@ console.log(await githubMarkdownCss({
 		// The theme to use for dark theme.
 		dark: 'dark',
 		// If `true`, will return a list of available themes instead of the CSS.
-		list = false,
+		list: false,
 		// If `true`, will preserve the block of variables for a given theme even if
 		// only exporting one theme. By default, variables are applied to the rules
 		// themselves and the resulting CSS will not contain any `var(--variable)`.
-		preserveVariables = false,
+		preserveVariables: false,
 		// Only output the color variables part of the CSS. Forces
 		// `preserveVariables` to be `true`.
-		onlyVariables = false,
+		onlyVariables: false,
 		// Only output the style part of the CSS without any variables. Forces
 		// `preserveVariables` to be `true` and ignores the theme values.
 		// Useful to get the base styles to use multiple themes.
-		onlyStyles = false,
+		onlyStyles: false,
 		// Set the root selector of the rendered Markdown body as it should appear
 		// in the output CSS. Defaults to `.markdown-body`.
-		rootSelector = '.markdown-body',
+		rootSelector: '.markdown-body',
 	}
 ));
 //=> '.markdown-body { …'