docs(readme): fix versioned openebs chart URL in command

[sleepymole]

Pull Request template

Please, go through these steps before you submit a PR.

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

The chart URL in command is incorrect.

kubectl apply -f https://github.com/openebs/charts/blob/gh-pages/versioned/3.0.0/lvm-operator.yaml

should be

$ kubectl apply -f https://raw.githubusercontent.com/openebs/charts/gh-pages/versioned/3.0.0/lvm-operator.yaml

What this PR does?:

Does this PR require any upgrade changes?:

If the changes in this PR are manually verified, list down the scenarios covered::

Any additional information for your reviewer? : Mention if this PR is part of any design or a continuation of previous PRs

Checklist:

• [x] Fixes #
• [x] 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:

[pawanpraka1]

@gozssky can you DCO sign this PR?

[sleepymole]

@gozssky can you DCO sign this PR?

Signed.