Merge pull request kubernetes#1902 from AndiLi99/master

Move CSI snapshot KEP into directory and add an extension for tightening validation

Author: k8s-ci-robot

keps/sig-storage/20190709-csi-snapshot.md renamed to keps/sig-storage/177-volume-snapshot/README.md

@@ -0,0 +1,54 @@
+title: CSI Snapshot
+kep-number: 177
+authors:
+  - "@jingxu97"
+  - "@xing-yang"
+owning-sig: sig-storage
+participating-sigs:
+  - sig-storage
+reviewers:
+  - "@msau42"
+  - "@saad-ali"
+  - "@thockin"
+approvers:
+  - "@msau42"
+  - "@saad-ali"
+  - "@thockin"
+prr-approvers:
+  - "@deads2k"
+editor: TBD
+creation-date: 2019-07-09
+last-updated: 2020-07-22
+status: implementable
+see-also:
+  - n/a
+replaces:
+  - n/a
+superseded-by:
+  - n/a
+
+# The target maturity stage in the current dev cycle for this KEP.
+stage: beta
+
+# The most recent milestone for which work toward delivery of this KEP has been
+# done. This can be the current (upcoming) milestone, if it is being actively
+# worked on.
+latest-milestone: "v1.20"
+
+# The milestone at which this feature was, or is targeted to be, at each stage.
+milestone:
+  alpha: ""
+  beta: "v1.17"
+  stable: "v1.20"
+
+# The following PRR answers are required at alpha release
+# List the feature gate name and the components for which it must be enabled
+feature-gates:
+  - name: VolumeSnapshotDataSource
+    components:
+      - kube-apiserver
+disable-supported: true
+
+# The following PRR answers are required at beta release
+metrics:
+