docs(localpv): Update examples to use recordsize=128k

[aceat64]

Why is this PR required? What issue does it fix?:

The default recordsize for ZFS datasets is 128k, and significantly better for most use-cases than 4k as shown in the StorageClass examples. Any users who copy the examples may see substantial performance hits and fragmentation in their datasets.

What this PR does?:

Updates the StorageClass examples to set a recordsize of 128k instead of 4k.

Does this PR require any upgrade changes?:

No, this is a documentation change only.

If the changes in this PR are manually verified, list down the scenarios covered::
n/a?

Any additional information for your reviewer? :
No

Checklist:

• Fixes #
• PR Title follows the convention of <type>(<scope>): <subject>
• Has the change log section been updated?
• Commit has unit tests
• Commit has integration tests
• (Optional) Are upgrade changes included in this PR? If not, mention the issue/PR to track:
• (Optional) If documentation changes are required, which issue on https://github.com/openebs/openebs-docs is used to track them:

[niladrih]

Hi @aceat64, thank you for this!