[premerge] Minor updates to cluster-management.md

Typos, and update the current autoscaling limit for the cluster.

premerge/cluster-management.md

diff --git a/premerge/cluster-management.md b/premerge/cluster-management.md
index 091b227..46567f4 100644
--- a/premerge/cluster-management.md
+++ b/premerge/cluster-management.md
@@ -40,7 +40,7 @@
 We should rename it at some point.
 
 To add a VM to the cluster, the VM has to come from a `pool`. A `pool` is
-a group of nodes withing a cluster that all have the same configuration.
+a group of nodes within a cluster that all have the same configuration.
 
 For example:
 A pool can say it contains at most 10 nodes, each using the `c2d-highcpu-32`
@@ -53,7 +53,7 @@
 - llvm-premerge-linux-service
 - llvm-premerge-windows
 
-Definitions for each pool is in [Architecture overview](architecture.md).
+Definitions for each pool are in [Architecture overview](architecture.md).
 
 If you click on a pool, example `llvm-premerge-linux`, you will see one
 instance group, and maybe several nodes.
@@ -64,8 +64,8 @@
 
 Then, we have the nodes. If you are looking at the panel during off hours,
 you might see no nodes at all: when no presubmit is running, no VM is on.
-If you are looking at the panel at peak time, you should see 4 instances.
-(Today, autoscale is capped at 4 instances).
+If you are looking at the panel at peak time, you should see 8 instances.
+(Today, autoscale is capped at 8 instances).
 
 If you click on a node, you'll see the CPU usage, memory usage, and can access
 the logs for each instance.