DOC-187 add migration article

Author: markzegarelli

src/_data/sidenav/strat.yml

@@ -93,6 +93,8 @@ sections:
     title: Analytics.js (Javascript) Source
   - path: /connections/sources/catalog/libraries/website/javascript/ajs-classic
     title: Analytics.js Classic
+  - path: connections/sources/catalog/libraries/website/javascript/migrate-to-ajs2
+    title: Migrate to Analytics.js 2.0
   - path: /connections/sources/catalog/libraries/website/javascript/supported-browsers
     title: Analytics.js supported browsers
   - path: /connections/sources/catalog/libraries/website/javascript/quickstart

src/connections/sources/catalog/libraries/website/javascript/migrate-to-ajs2.md

@@ -0,0 +1,34 @@
+---
+title: Migrate to A.js 2.0
+strat: ajs
+---
+
+Analytics.js 2.0 is fully backward compatible with Analytics.js Classic. To migrate your sources, follow the manual upgrade steps below, or see the schedule for automatic migration.
+
+## Manual migration
+
+To migrate a source to Analytics.js 2.0:
+
+1. In your Segment workspace, open the **Connections** page.
+2. Open the Javascript source you will migrate.
+3. On the **Settings** tab, open the **Analytics.js** category.
+4. Enable the flag for Analytics 2.0.
+5. Within 5 minutes, the source receives Analytics.js 2.0. No code or tag changes required.
+6. Open the Debugger to ensure that events are flowing as expected.
+
+## Automatic migration
+
+Analytics.js sources will migrate to Analytics.js 2.0 on the date below, according to the account tier. On the date listed, Segment will migrate all Analytics.js sources within the associated account tier.
+
+| Segment Plan | Upgrade Date |
+|--------------| -------------|
+| Free         | June 15, 2021|
+| Team         | July 6, 2021 | 
+| Business     | Q3, 2021     |
+
+> info ""
+> The plans and dates listed above are subject to change.
+
+## Revert to Analytics.js Classic
+
+Once a source moves to Analytics.js 2.0, you can follow the steps above in [Manual migration](#manual-migration) back to  roll back to Analytics.js Classic.