Add project name documentation to playdate_example.nimble

playdate_example/playdate_example.nimble

@@ -4,6 +4,9 @@ version       = "0.8.0"
 author        = "Samuele Zolfanelli"
 description   = "An example application using the Playdate Nim bindings"
 license       = "MIT"
+## The main entrypoint of your game. In this example the file `playdate_example/src/playdate_example.nim` is
+## the first nim file that is executed when the game is started
+## note that the value of bin must match the project folder name
 srcDir        = "src"
 bin           = @["playdate_example"]