provider/aws: Update S3 Bucket Object docs for KMS Key

website/source/docs/providers/aws/r/s3_bucket_object.html.markdown

@@ -23,6 +23,27 @@ resource "aws_s3_bucket_object" "object" {
 }
 ```
 
+### Encrypting with KMS Key
+
+```
+resource "aws_kms_key" "examplekms" {
+  description             = "KMS key 1"
+  deletion_window_in_days = 7
+}
+
+resource "aws_s3_bucket" "examplebucket" {
+  bucket = "examplebuckettftest"
+  acl    = "private"
+}
+
+resource "aws_s3_bucket_object" "examplebucket_object" {
+  key        = "someobject"
+  bucket     = "${aws_s3_bucket.examplebucket.bucket}"
+  source     = "index.html"
+  kms_key_id = "${aws_kms_key.examplekms.arn}"
+}
+```
+
 ## Argument Reference
 
 The following arguments are supported:
@@ -31,13 +52,17 @@ The following arguments are supported:
 * `key` - (Required) The name of the object once it is in the bucket.
 * `source` - (Required) The path to the source file being uploaded to the bucket.
 * `content` - (Required unless `source` given) The literal content being uploaded to the bucket.
-* `cache_control` - (Optional) Specifies caching behavior along the request/reply chain Read [w3c cache_control](http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9) for futher details.
+* `cache_control` - (Optional) Specifies caching behavior along the request/reply chain Read [w3c cache_control](http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9) for further details.
 * `content_disposition` - (Optional) Specifies presentational information for the object. Read [wc3 content_disposition](http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.5.1) for further information.
 * `content_encoding` - (Optional) Specifies what content encodings have been applied to the object and thus what decoding mechanisms must be applied to obtain the media-type referenced by the Content-Type header field. Read [w3c content encoding](http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.11) for further information.
 * `content_language` - (Optional) The language the content is in e.g. en-US or en-GB.
 * `content_type` - (Optional) A standard MIME type describing the format of the object data, e.g. application/octet-stream. All Valid MIME Types are valid for this input.
-* `etag` - (Optional) Used to trigger updates. The only meaningful value is `${md5(file("path/to/file"))}`
-* `kms_key_id` - (Optional) Specifies the AWS KMS key ID to use for object encryption.
+* `etag` - (Optional) Used to trigger updates. The only meaningful value is `${md5(file("path/to/file"))}`. 
+This attribute is not compatible with `kms_key_id`
+* `kms_key_id` - (Optional) Specifies the AWS KMS Key ID to use for object encryption. 
+This value is a fully qualified **ARN** of the KMS Key. If using `aws_kms_key`,
+use the exported `arn` attribute:  
+      `kms_key_id = "${aws_kms_key.foo.arn}"`
 
 Either `source` or `content` must be provided to specify the bucket content.
 These two arguments are mutually-exclusive.