Update screen-tracking docs to include initial route (#1373)

Co-authored-by: Satyajit Sahoo <satyajit.happy@gmail.com>

Author: ethanneff

versioned_docs/version-6.x/screen-tracking.md

@@ -32,6 +32,9 @@ export default () => {
       ref={navigationRef}
       onReady={() => {
         routeNameRef.current = navigationRef.getCurrentRoute().name;
+
+        // Replace the line below to add the tracker from a mobile analytics SDK
+        await trackScreenView(routeNameRef.current);
       }}
       onStateChange={async () => {
         const previousRouteName = routeNameRef.current;

versioned_docs/version-7.x/screen-tracking.md

@@ -149,6 +149,9 @@ export default function App() {
       ref={navigationRef}
       onReady={() => {
         routeNameRef.current = navigationRef.current.getCurrentRoute().name;
+
+        // Replace the line below to add the tracker from a mobile analytics SDK
+        await trackScreenView(routeNameRef.current);
       }}
       onStateChange={async () => {
         const previousRouteName = routeNameRef.current;

versioned_docs/version-8.x/screen-tracking.md

@@ -149,6 +149,9 @@ export default function App() {
       ref={navigationRef}
       onReady={() => {
         routeNameRef.current = navigationRef.current.getCurrentRoute().name;
+
+        // Replace the line below to add the tracker from a mobile analytics SDK
+        await trackScreenView(routeNameRef.current);
       }}
       onStateChange={async () => {
         const previousRouteName = routeNameRef.current;