Give example values for file parameter in getStepLogs

The `file` request parameter in https://github.com/AdobeDocs/cloudmanager-api-docs/blob/b6c0678a414f112dba41e3bc8ecbf324385cd20f/swagger-specs/api.yaml#L751 does not come with a description nor example values which would explain valid values here. By looking at the CloudManager Web UI I figured out there is only `sonarLogFile` supported now in step code scanning.

Open swagger-specs/api.yaml at the getStepLogs definition around line 751 and inspect the file request parameter. Document the supported value sonarLogFile with a description and example, then verify the OpenAPI entry clearly explains the valid value.

Written by the indexing model from the issue text.