Update README to remove local activities experimental warning (#1334)

Remove experimental warning for local activities in README.

Co-authored-by: tconley1428 <tconley1428@gmail.com>

Author: donald-pinckney

README.md

@@ -828,7 +828,6 @@ Some things to note about the above code:
   capabilities are needed.
 * Local activities work very similarly except the functions are `workflow.start_local_activity()` and
   `workflow.execute_local_activity()`
-  * ⚠️Local activities are currently experimental
 * Activities can be methods of a class. Invokers should use `workflow.start_activity_method()`,
   `workflow.execute_activity_method()`, `workflow.start_local_activity_method()`, and
   `workflow.execute_local_activity_method()` instead.