Create pod eviction concept and glossary entries

- Created glossary entries for manual and kubelet eviction
  - Created node-pressure-eviction.md and api-eviction.md
  - Merged content from eviction-policy.md and out-of-resource.md
  - Added note to kube-scheduler about node conditions
  - Deleted eviction-policy and out-of-resource.md
  - Redirected old topics
  - Change topic weights

content/en/docs/concepts/scheduling-eviction/api-eviction.md

@@ -0,0 +1,19 @@
+---
+title: API-initiated Eviction
+content_type: concept
+weight: 70
+---
+
+{{< glossary_definition term_id="api-eviction" length="short" >}} </br>
+
+You can request eviction by directly calling the Eviction API 
+using a client of the kube-apiserver, like the `kubectl drain` command. 
+This creates an `Eviction` object, which causes the API server to terminate the Pod. 
+
+API-initiated evictions respect your configured [`PodDisruptionBudgets`](/docs/tasks/run-application/configure-pdb/)
+and [`terminationGracePeriodSeconds`](/docs/concepts/workloads/pods/pod-lifecycle#pod-termination). 
+
+## {{% heading "whatsnext" %}}
+
+* Learn about [Node-pressure Eviction](/docs/concepts/scheduling-eviction/node-pressure-eviction/)
+* Learn about [Pod Priority and Preemption](/docs/concepts/scheduling-eviction/pod-priority-preemption/)