docs(content): add issue URLs to problem pages and restructure guides into appendix

apps/docs/content/(05-decision-space)/1d-dynamic-programming/70-climbing-stairs.mdx

@@ -6,6 +6,7 @@ topics:
   - { name: "Math", slug: "math" }
   - { name: "Dynamic Programming", slug: "dynamic-programming" }
   - { name: "Memoization", slug: "memoization" }
+issue: "https://github.com/prdlk/leetcode/issues/157"
 sidebar:
   label: 'Climbing Stairs'
   badge: 'Easy'