Add VM image semantic conventions (#405)

Author: kbrockhoff

specification/data-resource-semantic-conventions.md

@@ -118,6 +118,9 @@ Attributes defining a computing instance (e.g. host).
 | host.id | Unique host id.<br/> For Cloud this must be the instance_id assigned by the cloud provider | `opentelemetry-test` |
 | host.name | Name of the host.<br/> It may contain what `hostname` returns on Unix systems, the fully qualified, or a name specified by the user. | `opentelemetry-test` |
 | host.type | Type of host.<br/> For Cloud this must be the machine type.| `n1-standard-1` |
+| host.image.name | Name of the VM image or OS install the host was instantiated from. | `infra-ami-eks-worker-node-7d4ec78312`, `CentOS-8-x86_64-1905` |
+| host.image.id | VM image id. For Cloud, this value is from the provider. | `ami-07b06b442921831e5` |
+| host.image.version | The version string of the VM image as defined in [Version Attributes](#version-attributes). | `0.1` |
 
 ## Environment