Change log for STEELHEAD

Date	Changes
2024-01-12	Enhancement: - Added Grok patterns to support new pattern of SYSLOG logs.
2022-08-08	Enhancement: - The field "agent.ephemeral_id" is mapped to "additional.fields[n]". - The field "tags" is mapped to "additional.fields[n].list_value[n]". - The field "logstash.irm_environment" is mapped to "additional.fields[n]". - The field "logstash.irm_site" is mapped to "additional.fields[n]". - The field "logstash.irm_region" is mapped to "additional.fields[n]". - The field "host.hostname" is mapped to "target.hostname". - The field "host.id" is mapped to "target.asset_id". - The field "host.architecture" is mapped to "target.asset.hardware[n].cpu_platform". - The field "host.ip[n]" is mapped to "target.ip". - The field "host.mac[n]" is mapped to "target.mac". - The field "host.os.platform" is mapped to "target.platform". - The field "host.os.version" is mapped to "target.platform_version". - The field "host.os.kernel" is mapped to "target.platform_patch_level". - The field "agent.type" and "agent.id" are mapped to "intermediary.asset_id". - The field "event.category[n]" is mapped to "security_result.category_details[n]". - The field "syslog_severity" is mapped to "security_result.severity" and "security_result.severity_details". - The field "network.community_id" is mapped to "network.community_id". - The field "logstash.ingest.timestamp" is mapped to "metadata.ingested_timestamp". - The field "logstash.collect.host" is mapped to "observer.hostname" or "observer.ip" accordingly.