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

apps/docs/content/(01-linear-structures)/prefix-sum/560-subarray-sum-equals-k.mdx

@@ -1,7 +1,7 @@
 ---
 title: '560. Subarray Sum Equals K'
 description: Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k
-icon: line-dot-left-horizontal
+icon: dot
 sidebar:
   label: 'Subarray Sum Equals K'
   badge: 'Medium'