Update RootA_Specification.md

Author: UncoderIO

RootA_Specification.md

@@ -231,7 +231,6 @@ Possible Values:
 - `logscale-lql-query` for Falcon LogScale Query
 - `mde-kql-query` for Microsoft Defender for Endpoint Query
 - `qradar-aql-query` for IBM QRadar Query
-- `sigma-yml-rule` for Sigma Rule
 - `athena-sql-query` for AWS Athena Query (Security Lake)
 - `chronicle-yaral-query` for Chronicle Security Query