Update kube-scheduler.md (#38264)

* Update kube-scheduler.md

A clearer way to write this paragraph explaining the scheduler.

Previous version: For every newly created pod or other unscheduled pods, kube-scheduler selects an optimal node for them to run on. However, every container in pods has different requirements for resources and every pod also has different requirements. Therefore, existing nodes need to be filtered according to the specific scheduling requirements.

Proposed version: Kube-scheduler selects an optimal node to run newly created or not yet scheduled (unscheduled) pods. Since containers in pods, and pods themselves have different requirements, existing nodes need to be filtered according to the specific scheduling requirements.

* Update kube-scheduler.md

I tried merging both our versions to make it a bit more concise, since feasibility is discussed in the subsequent paragraphs.

Author: hamzalsheikh

content/en/docs/concepts/scheduling-eviction/kube-scheduler.md

@@ -32,11 +32,12 @@ is the default scheduler for Kubernetes and runs as part of the
 kube-scheduler is designed so that, if you want and need to, you can
 write your own scheduling component and use that instead.
 
-For every newly created pod or other unscheduled pods, kube-scheduler
-selects an optimal node for them to run on. However, every container in
-pods has different requirements for resources and every pod also has
-different requirements. Therefore, existing nodes need to be filtered
-according to the specific scheduling requirements.
+Kube-scheduler selects an optimal node to run newly created or not yet
+scheduled (unscheduled) pods. Since containers in pods - and pods themselves -
+can have different requirements, the scheduler filters out any nodes that
+don't meet a Pod's specific scheduling needs. Alternatively, the API lets
+you specify a node for a Pod when you create it, but this is unusual
+and is only done in special cases.
 
 In a cluster, Nodes that meet the scheduling requirements for a Pod
 are called _feasible_ nodes. If none of the nodes are suitable, the pod