fix: wrong git clone url in readme

[m-v-k]

1. Why is this change required? -> wrong url in readme file
2. What problem does it solve? -> correct the url
3. What scenario does it contribute to? -> contribution / usage
4. If it fixes an open issue, please link to the issue here. -> it doesn't

• [ x] The code builds clean without any errors or warnings
• [x ] The PR follows SK Contribution Guidelines (https://github.com/microsoft/semantic-kernel-starters/blob/main/CONTRIBUTING.md)
• [x ] The code follows the .NET coding conventions (https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions) verified with dotnet format
• [x ] All unit tests pass, and I have added new tests where possible
• [x ] I didn't break anything :smile: