docs: Update README.md

[AndrewBrook-Google]

Reverted one occurrence of "genai-toolbox" which should not be updated to "mcp-toolbox" since it's in the explanation of why we had the old name.

Description

Should include a concise description of the changes (bug or feature), it's
impact, along with a summary of the solution

PR Checklist

Thank you for opening a Pull Request! Before submitting your PR, there are a
few things you can do to make sure it goes smoothly:

• Make sure you reviewed
  CONTRIBUTING.md
• Make sure to open an issue as a
  bug/issue
  before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)
• Make sure to add ! if this involve a breaking change

🛠️ Fixes #<issue_number_goes_here>

[gemini-code-assist]

Code Review

This pull request updates the README.md to correct a historical repository URL reference. Feedback was provided to improve the phrasing for conciseness and to use full HTTPS URLs for better link resolution. Additionally, the reviewer pointed out that the PR title and description must be updated to comply with the repository's style guide regarding Conventional Commits and issue references.

[github-actions]

🧨 Preview deployments removed.

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