[ZEPPELIN-6488] Refresh stale apache/zeppelin:0.10.0 Docker tags in the quickstart docs

[xhaktm00]

What is this PR for?

The three docker run examples in the "Using the official docker image" section of docs/quickstart/install.md pin the image to apache/zeppelin:0.10.0, a release from several years ago. A first-time user following the Quickstart literally ends up running an image far behind the current docs.

This PR:

• updates the three examples to apache/zeppelin:0.12.1, the latest release tag currently available on Docker Hub
• adds a one-line note next to the examples pointing to the apache/zeppelin tags page so readers can find the latest tag, preventing the docs from silently rotting at the next release

Out of scope (open for discussion): the same stale tag also appears in docs/interpreter/python.md, docs/interpreter/flink.md (x2), docs/interpreter/spark.md, and docs/interpreter/r.md, and docs/quickstart/docker.md uses FROM apache/zeppelin:0.8.0. Would you prefer that I align those in this PR as well, or split them into a follow-up? I would be happy to do either.

What type of PR is it?

Documentation

What is the Jira issue?

• ZEPPELIN-6488

How should this be tested?

Documentation-only change, no unit tests required.

• grep -rn "apache/zeppelin:0.10.0" docs/quickstart/install.md reports no occurrences
• Verified the updated command works: docker run -p 8080:8080 --rm --name zeppelin apache/zeppelin:0.12.1 pulls the image and Zeppelin responds on the mapped port (/api/version returns 0.12.1)

Screenshots (if appropriate)

N/A

Questions:

• Does the license files need to update? No
• Is there breaking changes for older versions? No
• Does this needs documentation? No (this is a documentation change)