Update logging-loki-pod-placement.adoc

- Need to remove additional nodeSelector and tolerations from Lokistack CR
- Here is the documentation link: 
https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html/logging/scheduling-resources#logging-loki-pod-placement_logging-taints-tolerations
- nodeSelector and tolerations are mentioned twice under the distributor field of Lokistack CR. 
~~~
    distributor:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved 
~~~

- values for both nodeSelector and tolerations are the same.
- Keeping it twice is not required and it is an unnecessary configuration.
- Hence need to remove additional nodeSelector and tolerations from the documentation.

- Here is the updated look:
~~~
    distributor:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved 
~~~

Author: prithvipatil97

modules/logging-loki-pod-placement.adoc

@@ -84,15 +84,6 @@ spec:
       - effect: NoExecute
         key: node-role.kubernetes.io/infra
         value: reserved
-      nodeSelector:
-        node-role.kubernetes.io/infra: ""
-      tolerations:
-      - effect: NoSchedule
-        key: node-role.kubernetes.io/infra
-        value: reserved
-      - effect: NoExecute
-        key: node-role.kubernetes.io/infra
-        value: reserved
     indexGateway:
       nodeSelector:
         node-role.kubernetes.io/infra: ""