Fix wrong bundle name and add clarification

[devguyio]

Description of the change: Fixes a wrong bundle name (memcached, should be nginx) and adds more clarification about how to override image tag name so that the user knows how to complete the tutorial.

Motivation for the change: While following the tutorial I found the wrong bundle name, then I wasn't able to do the bundle-push step since I had a different image tag. I had to dig in the Makefile to find out how to override that. The docs showed how to override IMG, so it's inconsistent not to state how to override IMAGE_TAG_BASE, which a user will need to do if they overrode IMG.

Checklist

If the pull request includes user-facing changes, extra documentation is required:

• [ ] Add a new changelog fragment in changelog/fragments (see changelog/fragments/00-template.yaml)
• [x] Add or update relevant sections of the docs website in website/content/en/docs

[openshift-ci[bot]]

New changes are detected. LGTM label has been removed.

[openshift-ci[bot]]

@devguyio: PR needs rebase.

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[openshift-bot]

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/lifecycle stale

[openshift-bot]

Stale issues rot after 30d of inactivity.

Mark the issue as fresh by commenting /remove-lifecycle rotten. Rotten issues close after an additional 30d of inactivity. Exclude this issue from closing by commenting /lifecycle frozen.

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/lifecycle rotten /remove-lifecycle stale

[openshift-bot]

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Reopen the issue by commenting /reopen. Mark the issue as fresh by commenting /remove-lifecycle rotten. Exclude this issue from closing again by commenting /lifecycle frozen.

/close

[openshift-ci[bot]]

@openshift-bot: Closed this PR.

In response to this:

Rotten issues close after 30d of inactivity.

Reopen the issue by commenting /reopen. Mark the issue as fresh by commenting /remove-lifecycle rotten. Exclude this issue from closing again by commenting /lifecycle frozen.

/close

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