docs: added registered trademarks to mentions of Apache Druid and Kafka

[avaamsel]

Changes: Added registered trademark symbol to mentions of Apache® Druid and Apache Kafka® throughout the docs

This PR has:

• been self-reviewed.

[317brian]

LGTM. There's one minor nit. On design/index there's an Apache in the page title. I think some other Apache projects include that when tagging the registered trademark.

This is a good start for us to get closer to checking the ® box. There are a few other Apache products that can be tackled down the line.

[FrankChen021]

Severity	Findings
P0	0
P1	0
P2	0
P3	1
Total	1

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This is an automated review by Codex GPT-5.5

[FrankChen021]

Severity	Findings
P0	0
P1	0
P2	0
P3	1
Total	1

Severity	Findings
P0	0
P1	0
P2	0
P3	1
Total	1

Reviewed 172 of 172 changed files.

Found 1 issue: registered-trademark HTML entities were inserted into YAML front matter metadata instead of Markdown body text.

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This is an automated review by Codex GPT-5.5

[FrankChen021]

The previously reported YAML-front-matter trademark entity issue remains in four unchanged description: metadata fields; the latest update fixes the Kafka tutorial title metadata case, and I found no new issues.

Reviewed 172 of 172 changed files.

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This is an automated review by Codex GPT-5.5