Update page.mdx (#10847)

Updated the if-else example condition for when input.is_active is false.

www/apps/book/app/learn/fundamentals/workflows/conditions/page.mdx

@@ -109,7 +109,7 @@ const workflow = createWorkflow(
     const notIsActiveResult = when(
       input,
       (input) => {
-        return input.is_active
+        return !input.is_active
       }
     ).then(() => {
       return notIsActiveStep()