[remark-callouts/package.json][xs]: fix export path

.changeset/poor-pots-look.md

@@ -0,0 +1,5 @@
+---
+'@portaljs/remark-callouts': patch
+---
+
+Fix: incorrect path to styles.css in package.json exports field.

packages/remark-callouts/package.json

@@ -42,6 +42,6 @@
       "import": "./dist/index.js",
       "require": "./dist/index.cjs"
     },
-    "./styles.css": "./styles.css"
+    "./styles.css": "./dist/styles.css"
   }
 }