add migration docs

Author: mydea

MIGRATION.md

@@ -15,8 +15,10 @@ In v8, the Span class is heavily reworked. The following properties & methods ar
 * `span.toContext()`: Access the fields directly instead.
 * `span.updateWithContext(newSpanContext)`: Update the fields directly instead.
 * `span.setName(newName)`: Use `span.updateName(newName)` instead.
-* `span.toTraceparent()`: use `spanToTraceHeader(span)` util instead.
-* `span.getTraceContext()`: Use `spanToTraceContext(span)` utility function instead.
+* `span.toTraceparent()`: use `spanToTraceHeader(span)` instead.
+* `span.getTraceContext()`: Use `spanToTraceContext(span)` instead.
+* `span.name`: Use `spanGetName(span)` instead.
+* `span.description`: Use `spanGetName(span)` instead.
 
 ## Deprecate `pushScope` & `popScope` in favor of `withScope`
 
@@ -57,7 +59,7 @@ Sentry.init({
     const lastCapturedEventId = event.event_id;
 
     // Do something with `lastCapturedEventId` here
-    
+
     return event;
   },
 });