Update based on review feedback

Ensure all changes are part of spec.md, and csi.proto is generated by "make".
Mark new fields as alpha.
Include a top-level note about quarantine states.

Author: bswartz

csi.proto

@@ -773,8 +773,9 @@ message ControllerUnpublishVolumeRequest {
   // The SP MAY make the volume inaccessible even when this field is
   // false.
   // This is an OPTIONAL field.
-  bool fence = 4;
+  bool fence = 4 [(alpha_field) = true];
 }
+
 message ControllerUnpublishVolumeResponse {
   // Intentionally empty.
 }
@@ -1057,7 +1058,7 @@ message ControllerServiceCapability {
 
       // Indicates the SP supports ControllerUnpublishVolume.fence
       // field.
-      UNPUBLISH_FENCE = 13;
+      UNPUBLISH_FENCE = 13 [(alpha_enum_value) = true];
     }
 
     Type type = 1;
@@ -1301,7 +1302,7 @@ message NodeUnstageVolumeRequest {
   // CO MUST NOT set this field to true unless SP has the
   // FORCE_UNPUBLISH node capability.
   // This in an OPTIONAL field.
-  bool force = 3;
+  bool force = 3 [(alpha_field) = true];
 }
 
 message NodeUnstageVolumeResponse {
@@ -1392,7 +1393,7 @@ message NodeUnpublishVolumeRequest {
   // CO MUST NOT set this field to true unless SP has the
   // FORCE_UNPUBLISH node capability.
   // This in an OPTIONAL field.
-  bool force = 3;
+  bool force = 3 [(alpha_field) = true];
 }
 
 message NodeUnpublishVolumeResponse {
@@ -1508,7 +1509,7 @@ message NodeServiceCapability {
       // field. Also indicates that the node supports the
       // NodeUnstageVolume.force field if it also has the
       // STAGE_UNSTAGE_VOLUME capability.
-      FORCE_UNPUBLISH = 5;
+      FORCE_UNPUBLISH = 5 [(alpha_enum_value) = true];
     }
 
     Type type = 1;