Add the following postCreateCommand to the body of the file before the last } (Edit the .devcontainer/devcontainer.json file)

Author: RomaniukNatalia

.devcontainer/devcontainer.json

@@ -20,4 +20,6 @@
         ]
     }
 }
+ ,
+ "postCreateCommand": "echo '# Writing code upon codespace creation!'  >> codespace.md"
 }