docs(docs): add page icon frontmatter to problem pages

apps/docs/content/(03-hierarchical)/trie/208-implement-trie-prefix-tree.mdx

@@ -1,6 +1,7 @@
 ---
 title: '208. Implement Trie (Prefix Tree)'
 description: A trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker
+icon: line-dot-left-horizontal
 sidebar:
   label: 'Implement Trie (Prefix Tree)'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/trie/211-design-add-and-search-words-data-structure.mdx

@@ -1,6 +1,7 @@
 ---
 title: '211. Design Add and Search Words Data Structure'
 description: Design a data structure that supports adding new words and finding if a string matches any previously added string
+icon: line-dot-left-horizontal
 sidebar:
   label: 'Design Add and Search Words Data Structure'
   badge: 'Medium'