algorithms(rank-balanced-trees): add skeleton for AVL

Signed-off-by: Matej Focko <me@mfocko.xyz>

algorithms/99-rank-balanced-trees/01-avl.md

@@ -0,0 +1,33 @@
+---
+id: avl
+slug: /rank-balanced-trees/avl
+title: AVL tree
+description: |
+  Explaining the idea behind the AVL tree.
+tags:
+  - balanced trees
+  - avl tree
+last_update:
+  date: 2024-06-30
+---
+
+Let's start by checking out the AVL tree. We will cover the historic context
+first, then go through the idea behind it and finally we will be able to discuss
+the insertion and deletion corrections that are used to maintain the property of
+a balanced tree.
+
+## Historic context
+
+_TODO_
+
+## Idea
+
+_TODO_
+
+## Insertion
+
+_TODO_
+
+## Deletion
+
+_TODO_