feat(python): Add enable_logs, before_send_log to 3.x migration guide (#14512)

We'll be changing this in 3.0, adding to migration guide.

Author: sentrivana

docs/platforms/python/migration/2.x-to-3.x.mdx

@@ -57,6 +57,23 @@ The `profiles_sample_rate` and `profiler_mode` options previously nested under `
   )
 ```
 
+The `enable_logs` and `before_send_log` options previously nested under `_experiments` have been removed. They're replaced by top-level options of the same name:
+
+```python diff
+
+  def my_before_send_log(log, hint):
+      ...
+
+  sentry_sdk.init(
+-     _experiments={
+-         "enable_logs": True,
+-         "before_send_log": my_before_send_log,
+-     },
++     enable_logs=True,
++     before_send_log=my_before_send_log,
+  )
+```
+
 ## API Changes
 
 `add_attachment()` is now a part of the top-level level API and should be imported and used directly from `sentry_sdk`.