Add content for k-d trees and skip lists

content/roadmaps/103-computer-science/content/122-kd-trees.md

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-# Kd trees
+# K-D Trees
+
+K-D Trees are a data structure that allow for fast nearest neighbor search in high dimensional spaces. They are a generalization of binary search trees, and are used in a variety of applications, including computer vision and computational geometry.
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='red' badgeText='Watch' href='https://www.youtube.com/watch?v=Y4ZgLlDfKDg'>K-D Tree Algorithm</BadgeLink>
+<BadgeLink colorScheme='red' badgeText='Watch' href='https://www.youtube.com/watch?v=BK5x7IUTIyU'>K-d Trees - Computerphile</BadgeLink>

content/roadmaps/103-computer-science/content/123-skip-lists.md

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-# Skip lists
+# Skip Lists
+
+Skip lists are a data structure that allows you to perform operations on a sorted list in O(log n) time. Skip lists are a probabilistic data structure, which means that the probability of a certain operation taking a certain amount of time is a certain value. In the case of skip lists, the probability of an operation taking O(log n) time is 1.
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='red' badgeText='Watch' href='https://www.youtube.com/watch?v=2g9OSRKJuzM&index=10&list=PLUl4u3cNGP6317WaSNfmCvGym2ucw3oGp'>Randomization: Skip Lists</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://en.wikipedia.org/wiki/Skip_list'>Skip Lists - Wikipedia</BadgeLink>