Update the comments for the v2 deprecation levels to make them clearer

Signed-off-by: Benjamin Wang <[email protected]>

server/config/v2_deprecation.go

@@ -17,47 +17,50 @@ package config
 type V2DeprecationEnum string
 
 const (
-	// No longer supported in v3.6
+	// V2Depr0NotYet means v2store isn't deprecated yet.
+	// Default in v3.5, and no longer supported in v3.6.
 	V2Depr0NotYet = V2DeprecationEnum("not-yet")
-	// No longer supported in v3.6
-	//
-	// Deprecated: Please use V2Depr0NotYet.
+
+	// Deprecated: to be decommissioned in 3.7. Please use V2Depr0NotYet.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_0_NOT_YET = V2Depr0NotYet
-	// Default in v3.6.  Meaningful v2 state is not allowed.
-	// The V2 files are maintained for v3.5 rollback.
 
-	V2Depr1WriteOnly = V2DeprecationEnum("write-only")
+	// V2Depr1WriteOnly means only writing v2store is allowed.
 	// Default in v3.6.  Meaningful v2 state is not allowed.
 	// The V2 files are maintained for v3.5 rollback.
-	//
-	// Deprecated: Please use V2Depr1WriteOnly.
+	V2Depr1WriteOnly = V2DeprecationEnum("write-only")
+
+	// Deprecated: to be decommissioned in 3.7. Please use V2Depr1WriteOnly.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_1_WRITE_ONLY = V2Depr1WriteOnly
 
-	// V2store is WIPED if found !!!
+	// V2Depr1WriteOnlyDrop means v2store is WIPED if found !!!
+	// Will be default in 3.7.
 	V2Depr1WriteOnlyDrop = V2DeprecationEnum("write-only-drop-data")
-	// V2store is WIPED if found !!!
-	//
-	// Deprecated: Pleae use V2Depr1WriteOnlyDrop.
+
+	// Deprecated: to be decommissioned in 3.7. Pleae use V2Depr1WriteOnlyDrop.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_1_WRITE_ONLY_DROP = V2Depr1WriteOnlyDrop
 
-	// V2store is neither written nor read. Usage of this configuration is blocking
+	// V2Depr2Gone means v2store is completely gone. The v2store is
+	// neither written nor read. Anything related to v2store will be
+	// cleaned up in v3.8. Usage of this configuration is blocking
 	// ability to rollback to etcd v3.5.
 	V2Depr2Gone = V2DeprecationEnum("gone")
-	// V2store is neither written nor read. Usage of this configuration is blocking
-	// ability to rollback to etcd v3.5.
-	//
-	// Deprecated: Please use V2Depr2Gone
+
+	// Deprecated: to be decommissioned in 3.7. Please use V2Depr2Gone.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_2_GONE = V2Depr2Gone
 
-	// Default deprecation level.
+	// V2DeprDefault is the default deprecation level.
 	V2DeprDefault = V2Depr1WriteOnly
-	// Default deprecation level.
-	//
-	// Deprecated: Please use V2DeprDefault.
+
+	// Deprecated: to be decommissioned in 3.7. Please use V2DeprDefault.
+	// TODO: remove in 3.7
 	//revive:disable-next-line:var-naming
 	V2_DEPR_DEFAULT = V2DeprDefault
 )