Update SIG Autoscaling in sigs.yaml

This updates the mission statement for SIG Autoscaling to correspond to
the scope of SIG Autoscaling in the charter.

It also ensures that SIG Autoscaling has the right subprojects listed (cluster
autoscaler, vertical pod autoscaler, horizontal-pod-autoscaler, and
scale-client), moving the metrics project to SIG instrumentation where it
belongs.

Author: DirectXMan12

sigs.yaml

@@ -305,10 +305,11 @@ sigs:
   - name: Autoscaling
     dir: sig-autoscaling
     mission_statement: >
-      Covers autoscaling of clusters, horizontal and vertical autoscaling of pods,
-      setting initial resources for pods, topics related to monitoring pods and
-      gathering their metrics (e.g. Heapster)
-    charter_link:
+      Covers development and maintenance of componets for automated scaling in
+      Kubernetes.  This includes automated vertical and horizontal pod
+      autoscaling, initial resource estimation, cluster-proportional system
+      component autoscaling, and autoscaling of Kubernetes clusters themselves.
+    charter_link: charter.md
     label: autoscaling
     leadership:
       chairs:
@@ -348,9 +349,12 @@ sigs:
     - name: autoscaler
       owners:
       - https://raw.githubusercontent.com/kubernetes/autoscaler/master/OWNERS
-    - name: metrics
+    - name: scale-client
       owners:
-      - https://raw.githubusercontent.com/kubernetes/metrics/master/OWNERS
+      - https://raw.githubusercontent.com/kubernetes/client-go/master/scale/OWNERS # doesn't exist yet
+    - name: horizntal-pod-autoscaler
+      owners:
+      - https://raw.githubusercontent.com/kubernetes/kubernetes/master/pkg/controller/podautoscaler/OWNERS
   - name: AWS
     dir: sig-aws
     mission_statement: >
@@ -1010,6 +1014,9 @@ sigs:
     - name: metrics-server
       owners:
       - https://raw.githubusercontent.com/kubernetes-incubator/metrics-server/master/OWNERS
+    - name: metrics
+      owners:
+      - https://raw.githubusercontent.com/kubernetes/metrics/master/OWNERS
   - name: Multicluster
     dir: sig-multicluster
     mission_statement: >