Add Categories and References

README.md

@@ -2,11 +2,36 @@
 
 > Today I Learned
 
+---
+
+## Categories
+* [JavaScript](#javascript)
+* [MacOS](#macos)
+* [Visual Studio Code](#visual-studio-code)
+
+---
+
+### JavaScript
+- [Base64 인코딩과 디코딩](JavaScript/base64-encode-and-decode.md)
 
 ### MacOS
 
 - [터미널에서 맥이 잠들지 않게 하기](macOS/prevent-mac-from-sleeping-with-terminal.md)
 
 ### Visual Studio Code
 
-- [Visual Studio Code 에서 markdown 파일만 trimTrailingWhitespace 옵션 끄기](VisualStudioCode/disable-trim-trailing-whitespace-for-markdown.md)
+- [Visual Studio Code 에서 markdown 파일만 trimTrailingWhitespace 옵션 끄기](VisualStudioCode/disable-trim-trailing-whitespace-for-markdown.md)
+
+
+---
+
+## References
+
+- These are TIL-related repositories that I referred to when I started TIL.
+  If someone starts TIL, I think the link of the users below will be helpful.
+
+* [@Integerous](https://github.com/Integerous/TIL)
+* [@jbranchaud](https://github.com/jbranchaud/til)
+* [@ksu3101](https://github.com/ksu3101/TIL)
+* [@milooy](https://github.com/milooy/TIL)
+* [@thoughtbot](https://github.com/thoughtbot/til)