misc: add TODOs to remove the redirects

algorithms/README.md

@@ -1,3 +1,5 @@
 # Algorithms
 
-The algorithms contents have been moved to the [website](https://yangshun.github.io/tech-interview-handbook/algorithms/algorithms-introduction).
+The contents have been moved to the [website](https://yangshun.github.io/tech-interview-handbook/algorithms/algorithms-introduction).
+
+<!-- TODO: Remove in future -->

preparing/README.md

@@ -1,3 +1,5 @@
 # Preparing
 
-The cheatsheet contents have been moved to the [website](https://yangshun.github.io/tech-interview-handbook/coding-round-overview).
+The contents have been moved to the [website](https://yangshun.github.io/tech-interview-handbook/coding-round-overview).
+
+<!-- TODO: Remove in future -->

preparing/cheatsheet.md

@@ -1,3 +1,5 @@
 # Cheatsheet
 
-The cheatsheet contents have been moved to the [website](https://yangshun.github.io/tech-interview-handbook/cheatsheet).
+The contents have been moved to the [website](https://yangshun.github.io/tech-interview-handbook/cheatsheet).
+
+<!-- TODO: Remove in future -->