Move custom property before arbitrary value

Author: philipp-spiess

src/docs/flex.mdx

@@ -14,8 +14,8 @@ export const description = "Utilities for controlling how flex items both grow a
     ["flex-auto", "flex: 1 1 auto;"],
     ["flex-initial", "flex: 0 1 auto;"],
     ["flex-none", "flex: none;"],
-    ["flex-[<value>]", "flex: <value>;"],
     ["flex-(<custom-property>)", "flex: var(<custom-property>);"],
+    ["flex-[<value>]", "flex: <value>;"],
   ]}
 />