docs(docs): add MDX pages for Median of Two Sorted Arrays and Largest Rectangle in Histogram and update site redirects

docs/site.json

@@ -178,6 +178,10 @@
       "from": "/3",
       "to": "/sliding-window/longest-substring-without-repeating-characters"
     },
+    {
+      "from": "/4",
+      "to": "/binary-search/median-of-two-sorted-arrays"
+    },
     {
       "from": "/11",
       "to": "/two-pointers/container-with-most-water"
@@ -278,6 +282,10 @@
       "from": "/78",
       "to": "/backtracking/subsets"
     },
+    {
+      "from": "/84",
+      "to": "/monotonic-stack/largest-rectangle-in-histogram"
+    },
     {
       "from": "/98",
       "to": "/binary-search-tree/validate-binary-search-tree"