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

apps/docs/content/(01-linear-structures)/monotonic-stack/739-daily-temperatures.mdx

@@ -7,6 +7,7 @@ topics:
   - { name: "Stack", slug: "stack" }
   - { name: "Monotonic Stack", slug: "monotonic-stack" }
 video: "cTBiBSnjO3c"
+issue: "https://github.com/prdlk/leetcode/issues/72"
 sidebar:
   label: 'Daily Temperatures'
   badge: 'Medium'

apps/docs/content/(01-linear-structures)/monotonic-stack/853-car-fleet.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Sorting", slug: "sorting" }
   - { name: "Monotonic Stack", slug: "monotonic-stack" }
 video: "Pr6T-3yB9RM"
+issue: "https://github.com/prdlk/leetcode/issues/73"
 sidebar:
   label: 'Car Fleet'
   badge: 'Medium'