[SPARK-52653] Fix *.operatorContainer to *.operatorPod.operatorContainer in operations.md

### What changes were proposed in this pull request?

This PR aims to fix the followings.

- `operatorDeployment.operatorContainer.jvmArgs` -> `operatorDeployment.operatorPod.operatorContainer.jvmArgs`
- `operatorDeployment.operatorContainer.env` -> `operatorDeployment.operatorPod.operatorContainer.env`
- `operatorDeployment.operatorContainer.envFrom` -> `operatorDeployment.operatorPod.operatorContainer.envFrom`
- `operatorDeployment.operatorContainer.probes` -> `operatorDeployment.operatorPod.operatorContainer.probes`
- `operatorDeployment.operatorContainer.securityContext` -> `operatorDeployment.operatorPod.operatorContainer.securityContext`
- `operatorDeployment.operatorContainer.resources` -> `operatorDeployment.operatorPod.operatorContainer.resources`

### Why are the changes needed?

The previous path is wrong. We need to use new path like the following.

```
$ helm install spark spark/spark-kubernetes-operator --set operatorDeployment.operatorContainer.jvmArgs="-XX:+PrintFlagsFinal"
NAME: spark
LAST DEPLOYED: Wed Jul  2 07:48:18 2025
NAMESPACE: default
STATUS: deployed
REVISION: 1

$ kubectl get deploy spark-kubernetes-operator -oyaml | grep -C1 OPERATOR_JAVA_OPTS
          value: -Dlog4j.configurationFile=/opt/spark-operator/conf/log4j2.properties
        - name: OPERATOR_JAVA_OPTS
          value: -Dfile.encoding=UTF8
```

```
$ helm install spark spark/spark-kubernetes-operator --set operatorDeployment.operatorPod.operatorContainer.jvmArgs="-XX:+PrintFlagsFinal"

$ kubectl get deploy spark-kubernetes-operator -oyaml | grep -C1 OPERATOR_JAVA_OPTS
          value: -Dlog4j.configurationFile=/opt/spark-operator/conf/log4j2.properties
        - name: OPERATOR_JAVA_OPTS
          value: -XX:+PrintFlagsFinal
```

### Does this PR introduce _any_ user-facing change?

No, this is a documentation update.

### How was this patch tested?

Manual review.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes apache#269 from dongjoon-hyun/SPARK-52653.

Authored-by: Dongjoon Hyun <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>

Author: dongjoon-hyun