docs: add Kafka compatibility documentation (fixes #3301)

[JPabasara]

Fixes #3301

Hello,

I noticed in Kafka compatibility wiki page(https://github.com/AutoMQ/automq/wiki/Compatibility-with-Apache-Kafka) is outdated .It still mentions v1.1.x as an upcoming release with Kafka 3.7.x, while AutoMQ is already at v1.6.5 running on Kafka 3.9.x

Since wiki pages can't be updated through a PR, I went ahead and created a new COMPATIBILITY.md in the repo root that covers:

A clear version matrix mapping AutoMQ releases to their Apache Kafka base (v1.0.x through v1.6.x)
A note clarifying that Kafka 4.x hasn't been adopted yet (which was the reporter's main question)
Ecosystem compatibility info (Clients, Connect, Streams, etc.)

I also updated the "100% Kafka Compatible" line in README.md to mention the actual version (3.9.x) and link to the new doc.

Version info was pulled from gradle.properties, docs/js/templateData.js, and the v1.6.5 release notes. The older version mappings (v1.0.x–v1.5.x) are based on what the wiki originally had, so please correct anything in this PR if you found any mismatches.

This is a docs only change. No code involved.

[CLAassistant]

All committers have signed the CLA.

[manmohak07]

On line 46, in compatibility.md which alternative documentation are we talking about? Please add the link as well.

"(Note: wiki may be outdated; refer to this document for the latest information)*"

You might want to bind a link to 'this document' above.

[JPabasara]

On line 46, in compatibility.md which alternative documentation are we talking about? Please add the link as well.

"(Note: wiki may be outdated; refer to this document for the latest information)*"

You might want to bind a link to 'this document' above.

"This document" here is a self reference. It refers to COMPATIBILITY.md file itself. I've added the link to it for extra clarity. Check the latest commit. If any other changes you expect, please share.

Thank you.

[manmohak07]

On line 46, in compatibility.md which alternative documentation are we talking about? Please add the link as well.
"(Note: wiki may be outdated; refer to this document for the latest information)*"
You might want to bind a link to 'this document' above.

"This document" here is a self reference. It refers to COMPATIBILITY.md file itself. I've added the link to it for extra clarity. Check the latest commit. If any other changes you expect, please share.

Thank you.

Okay. I think we can just add something like "Wiki might be outdated" and it should be fine.

[JPabasara]

On line 46, in compatibility.md which alternative documentation are we talking about? Please add the link as well.
"(Note: wiki may be outdated; refer to this document for the latest information)*"
You might want to bind a link to 'this document' above.

"This document" here is a self reference. It refers to COMPATIBILITY.md file itself. I've added the link to it for extra clarity. Check the latest commit. If any other changes you expect, please share.
Thank you.

Okay. I think we can just add something like "Wiki might be outdated" and it should be fine.

Hi, I simplified it to just "Wiki might be outdated" as you suggested. Please check the latest commit.