Added last_event_id() to the stuff that has been removed.

Author: antonpirker

MIGRATION_GUIDE.md

@@ -22,6 +22,7 @@ Looking to upgrade from Sentry SDK 1.x to 2.x? Here's a comprehensive list of wh
 - Removed support for Celery 3.\*.
 - Removed support for Django 1.8, 1.9, 1.10.
 - Removed support for Flask 0.\*.
+- Removed `last_event_id()` top level API. The last event Id is still returned by `capture_event()`, `capture_exception()` and `capture_message()` but the top level api `sentry_sdk.last_event_id()` has been removed. 
 - `sentry_sdk._functools` was removed.
 - A number of compatibility utilities were removed from `sentry_sdk._compat`: the constants `PY2` and `PY33`; the functions `datetime_utcnow`, `utc_from_timestamp`, `implements_str`, `contextmanager`; and the aliases `text_type`, `string_types`, `number_types`, `int_types`, `iteritems`, `binary_sequence_types`.
 - The deprecated `with_locals` configuration option was removed. Use `include_local_variables` instead. See https://docs.sentry.io/platforms/python/configuration/options/#include-local-variables.