Add question checklist

Author: dawsbot

README.md

@@ -2,6 +2,29 @@
 
 <br>
 
+## Question List:
+
+#### Chapter 1 
+- [x] 1.1 - [Is Unique](lib/data-structures/chapter-1/1_1.js)
+- [x] 1.2 - [Check Permutation](lib/data-structures/chapter-1/1_2.js)
+- [x] 1.3 - [URLify](lib/data-structures/chapter-1/1_3.js)
+- [x] 1.4 - [Palindrome Permutation](lib/data-structures/chapter-1/1_4.js)
+- [x] 1.5 - [One Away](lib/data-structures/chapter-1/1_5.js)
+- [x] 1.6 - [String Compression](lib/data-structures/chapter-1/1_6.js)
+- [x] 1.7 - [Rotate Matrix](lib/data-structures/chapter-1/1_7.js)
+- [x] 1.8 - [Zero Matrix](lib/data-structures/chapter-1/1_8.js)
+- [ ] 1.9 - String Rotation 
+
+#### Chapter 3
+- [ ] 3.1 - Three in One
+- [ ] 3.2 - Stack Min
+- [ ] 3.3 - Stack of Plates
+- [ ] 3.4 - Queue via Stacks
+- [x] 3.5 - [Sort Stack](lib/data-structures/chapter-3/3_5.js)
+- [ ] 3.6 - Animal Shelter
+
+<br>
+
 ## Install dependencies:
 ```bash
 npm install