docs: replace legacy line‑dot‑left‑horizontal icons with unified dot icon across docs

apps/docs/content/(01-linear-structures)/sliding-window/567-permutation-in-string.mdx

@@ -1,7 +1,7 @@
 ---
 title: '567. Permutation in String'
 description: Given two strings s1 and s2, return true if s2 contains a permutation of s1, or false otherwise
-icon: line-dot-left-horizontal
+icon: dot
 sidebar:
   label: 'Permutation in String'
   badge: 'Medium'