api-ref: Fix 'id' (attachment_id) parameters

At first, the 'attachment_id_resp' in parameters.yaml was defined
as 'required' in I3789a4ad36e30728024f2aa122403b0e53b1e741
for os-volume_attachments.inc.
Then it was changed to 'optional' in
I0c1d183c5aaf6fb796be30fa5627bd5644ea689f
for os-volumes.inc.
So currently 'id' (attachment_id) parameters in
os-volume_attachments.inc are wrong.
They should be 'required'. So fix them.

Change-Id: I403a9eb1b08a840cbb2b82cb37f1b49c6edb87c9
Closes-Bug: #1608842

api-ref/source/os-volume-attachments.inc

@@ -33,7 +33,7 @@ Response
 
   - volumeAttachments: volumeAttachments
   - device: device_resp
-  - id: attachment_id_resp
+  - id: attachment_id_required
   - serverId: server_id
   - volumeId: volumeId_resp
 
@@ -78,7 +78,7 @@ Response
 
   - volumeAttachment: volumeAttachment
   - device: device_resp
-  - id: attachment_id_resp
+  - id: attachment_id_required
   - serverId: server_id
   - volumeId: volumeId_resp
 
@@ -113,7 +113,7 @@ Response
 
   - volumeAttachment: volumeAttachment
   - device: device_resp
-  - id: attachment_id_resp
+  - id: attachment_id_required
   - serverId: server_id
   - volumeId: volumeId_resp
 

api-ref/source/parameters.yaml

@@ -991,6 +991,12 @@ attachment_device_resp:
   in: body
   required: false
   type: string
+attachment_id_required:
+  description: |
+    The UUID of the attachment.
+  in: body
+  required: true
+  type: string
 attachment_id_resp:
   description: |
     The UUID of the attachment.