File path to help doc

Author: microbit-robert

docs/on-start.md

@@ -0,0 +1,3 @@
+# on ML ... start
+
+Some documentation

pxt.json

@@ -8,6 +8,7 @@
   },
   "files": [
     "README.md",
+    "docs/on-start.md",
     "shims.d.ts",
     "enums.d.ts",
     "pxtextension.ts",

pxtextension.ts

@@ -56,6 +56,7 @@ namespace ml {
   //% weight=50
   //% parts="v2"
   //% group="micro:bit (V2)"
+  //% help=github:pxt-microbit-ml/docs/on-start
   export function onStart(event: MlEvent, body: () => void): void {
     event.onStartHandler = body;
     const wrappedBody = () => {