chore: Add license badge to README

[szepeviktor]

Add license badge and

• fix alt tags
• remove stray closing div
• fix free trial URL

From #1510

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[CLAassistant]

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[KaimingWan]

Thanks for your contribution. Since AutoMQ's code include multi licenses like revised BSL and Apache License etc., it's better for users to check the license by our license files rather than the license badge. Could you remove the license badges that may cause misunderstanding?

[szepeviktor]

Done.

[github-actions]

This PR is being marked as stale since it has not had any activity in 90 days. If you would like to keep this PR alive, please ask a committer for review. If the PR has merge conflicts, please update it with the latest from trunk (or appropriate release branch)

If this PR is no longer valid or desired, please feel free to close it. If no activity occurs in the next 30 days, it will be automatically closed.

[szepeviktor]

@KaimingWan Friendly ping 🏓