Fix wiki link color

packages/preset-themes/src/styles/nature.scss

@@ -29,8 +29,8 @@
 
   @import '@growi/core/scss/bootstrap/theming/apply-light';
 
-  --grw-wiki-link-color-rgb: var(--grw-primary-700-rgb);
-  --grw-wiki-link-hover-color-rgb: var(--grw-primary-600-rgb);
+  --grw-wiki-link-color-rgb: var(--grw-primary-600-rgb);
+  --grw-wiki-link-hover-color-rgb: var(--grw-primary-700-rgb);
 }
 
 // @use '@growi/core/scss/bootstrap/init' as bs;