Draw UML from VSCode

# Requirement: Java should be installed on your machine

1. Search PlantUML from Marketplace in VSCode

2. Install PlantUML

3. Create a file with the ".plantuml" extension
   ex) squence.plantuml

4. Start with "@startuml"

5. Write down some script code
   (reference: https://0x010.com/uploads/PlantUML_Language_Reference_Guide_ko.pdf)

6. End with "@enduml"

7. See the corresponding UML by typing "Alt + D"