api-ref: Fix wrong parameters in os-volumes.inc

In os-snapshots APIs, the display name is the snapshot name,
not the volume name.
The display description is the snapshot description,
not the volume description.
So fix them.

Change-Id: I33cd59b759c6f7c8eca8bd511ba43637e7b27c1c
Closes-Bug: #1611292

api-ref/source/os-volumes.inc

@@ -245,8 +245,8 @@ Response
   - snapshots: snapshots
   - id: snapshot_id
   - createdAt: created
-  - displayName: display_name
-  - displayDescription: display_description
+  - displayName: snapshot_name
+  - displayDescription: snapshot_description
   - size: size
   - status: snapshot_status
   - volumeId: volume_id
@@ -276,8 +276,8 @@ Request
 
   - snapshot: snapshot
   - volume_id: volume_id
-  - display_description: display_description_optional
-  - display_name: display_name_optional
+  - display_description: snapshot_description_optional
+  - display_name: snapshot_name_optional
   - force: force_snapshot
 
 **Example Create Snapshot**
@@ -293,8 +293,8 @@ Response
   - snapshot: snapshot
   - id: snapshot_id
   - createdAt: created
-  - displayName: display_name
-  - displayDescription: display_description
+  - displayName: snapshot_name
+  - displayDescription: snapshot_description
   - volumeId: volume_id
   - size: size
   - status: snapshot_status
@@ -323,8 +323,8 @@ Response
   - snapshots: snapshots
   - id: snapshot_id
   - createdAt: created
-  - displayName: display_name
-  - displayDescription: display_description
+  - displayName: snapshot_name
+  - displayDescription: snapshot_description
   - volumeId: volume_id
   - size: size
   - status: snapshot_status
@@ -362,8 +362,8 @@ Response
   - snapshot: snapshot
   - id: snapshot_id
   - createdAt: created
-  - displayName: display_name
-  - displayDescription: display_description
+  - displayName: snapshot_name
+  - displayDescription: snapshot_description
   - volumeId: volume_id
   - size: size
   - status: snapshot_status

api-ref/source/parameters.yaml

@@ -4014,6 +4014,18 @@ snapshot:
   in: body
   required: true
   type: object
+snapshot_description:
+  description: |
+    The snapshot description.
+  in: body
+  required: true
+  type: string
+snapshot_description_optional:
+  description: |
+    The snapshot description.
+  in: body
+  required: false
+  type: string
 snapshot_id:
   description: |
     The UUID for a snapshot.
@@ -4026,6 +4038,18 @@ snapshot_id_optional:
   in: body
   required: false
   type: string
+snapshot_name:
+  description: |
+    The snapshot name.
+  in: body
+  required: true
+  type: string
+snapshot_name_optional:
+  description: |
+    The snapshot name.
+  in: body
+  required: false
+  type: string
 snapshot_status:
   description: |
     The status of the snapshot.  Valid status values are: