KEP-127: Make implementation history a list

So it is rendered properly on github.

Signed-off-by: Rodrigo Campos <[email protected]>

Author: rata

keps/sig-node/127-user-namespaces/README.md

@@ -1269,9 +1269,9 @@ For each of them, fill in the following information by copying the below templat
 
 ## Implementation History
 
-2016: First iterations of this KEP, but code never landed upstream.
-Kubernetes 1.25: Support for stateless pods merged (alpha)
-Kubernetes 1.27: Support for stateless pods rework to rely on idmap mounts (alpha)
+- 2016: First iterations of this KEP, but code never landed upstream.
+- Kubernetes 1.25: Support for stateless pods merged (alpha)
+- Kubernetes 1.27: Support for stateless pods rework to rely on idmap mounts (alpha)
 
 <!--
 Major milestones in the lifecycle of a KEP should be tracked in this section.