Add explanation for attrs rather than props

app/assets/javascripts/monitoring/monitoring_app.js

@@ -28,6 +28,17 @@ export default (props = {}) => {
       },
       render(h) {
         return h('RouterView', {
+          // This is attrs rather than props because:
+          //  1. RouterView only actually defines one prop: `name`.
+          //  2. The RouterView [throws away other props][1] given to it, in
+          //     favour of those configured in the route config/params.
+          //  3. The Vue template compiler itself in general compiles anything
+          //     like <some-component :foo="bar" /> into roughly
+          //     h('some-component', { attrs: { foo: bar } }). Then later, Vue
+          //     [extract props from attrs and merges them with props][2],
+          //     matching them up according to the component's definition.
+          // [1]: https://github.com/vuejs/vue-router/blob/v3.4.9/src/components/view.js#L124
+          // [2]: https://github.com/vuejs/vue/blob/v2.6.12/src/core/vdom/helpers/extract-props.js#L12-L50
           attrs: {
             dashboardProps: this.dashboardProps,
           },