Change log for NGINX

Date Changes
2025-06-23 Enhancement:
- Added a Grok pattern to fetch only the required "user_agent" data and map it to "network.http.user_agent" UDM field.
- event.idm.read_only_udm.network.http.parsed_user_agent: Newly mapped `user_agent` raw log field with `event.idm.read_only_udm.network.http.parsed_user_agent` UDM field
2022-09-10 -Newly created parser.
-Created default parser and deleted customer specific parser.