Expand example explanation

As mentioned in  #17871 the current example can hide the fact that the module
path plays an important role. The example's explanation is expanded.

Moreover, the verb "attach" is replaced with "map" to make the vocabulary
consistent with the wording in the documentation of the terraform state.

website/docs/import/usage.html.md

@@ -32,19 +32,21 @@ remains constant.
 If desired, you can leave the body of the resource block blank for now and
 return to fill it in once the instance is imported.
 
-Now `terraform import` can be run to attach an existing instance to this
+Now `terraform import` can be run to map an existing instance to this
 resource configuration:
 
 ```shell
 $ terraform import aws_instance.example i-abcd1234
 ```
 
-This command locates the AWS instance with ID `i-abcd1234` and attaches
-its existing settings, as described by the EC2 API, to the name
-`aws_instance.example` in the Terraform state.
+This command locates the AWS instance with ID `i-abcd1234`. Then it maps
+the existing settings of the instance, as described by the EC2 API, to the
+name `aws_instance.example` of a module. In this example the module path
+implies that the root module is used. Finally, the mapping is saved in the
+Terraform state.
 
-It is also possible to import to resources in child modules and to single
-instances of a resource with `count` set. See
+It is also possible to import to resources in child modules, using their paths,
+and to single instances of a resource with `count` set. See
 [_Resource Addressing_](/docs/internals/resource-addressing.html) for more
 details on how to specify a target resource.