add podman scheme to doc examples (#860)

README.md

@@ -114,6 +114,7 @@ Sources can be explicitly provided with a scheme:
 
 ```
 docker:yourrepo/yourimage:tag          use images from the Docker daemon
+podman:yourrepo/yourimage:tag          use images from the Podman daemon
 docker-archive:path/to/yourimage.tar   use a tarball from disk for archives created from "docker save"
 oci-archive:path/to/yourimage.tar      use a tarball from disk for OCI archives (from Skopeo or otherwise)
 oci-dir:path/to/yourimage              read directly from a path on disk for OCI layout directories (from Skopeo or otherwise)

cmd/packages.go

@@ -42,6 +42,7 @@ const (
 
 	schemeHelpHeader = "You can also explicitly specify the scheme to use:"
 	imageSchemeHelp  = `    {{.appName}} {{.command}} docker:yourrepo/yourimage:tag          explicitly use the Docker daemon
+    {{.appName}} {{.command}} podman:yourrepo/yourimage:tag        	 explicitly use the Podman daemon
     {{.appName}} {{.command}} registry:yourrepo/yourimage:tag        pull image directly from a registry (no container runtime required)
     {{.appName}} {{.command}} docker-archive:path/to/yourimage.tar   use a tarball from disk for archives created from "docker save"
     {{.appName}} {{.command}} oci-archive:path/to/yourimage.tar      use a tarball from disk for OCI archives (from Skopeo or otherwise)

cmd/power_user.go

@@ -26,7 +26,7 @@ const powerUserExample = `  {{.appName}} {{.command}} <image>
 
   DEPRECATED - THIS COMMAND WILL BE REMOVED in v1.0.0
 
-  Only image sources are supported (e.g. docker: , docker-archive: , oci: , etc.), the directory source (dir:) is not supported.
+  Only image sources are supported (e.g. docker: , podman: , docker-archive: , oci: , etc.), the directory source (dir:) is not supported.
 
   All behavior is controlled via application configuration and environment variables (see https://github.com/anchore/syft#configuration)
 `