added citation to README.md type = inproceeding

[priyansh4320]

these are the changes

@inproceedings{"Microsoft Research, Redmond WA USA",
  author       =  {Wu Qingyun, Bansal Gargan, Zhang Jieyu, Wu Yiran, Zhang Shaokun, Zhu Eric, Li Beibin, Jiang Li, Zhang Xiaoyun, Wang Chi},
  title        = {AutoGen: Enabling Next-Gen LLM Applications via Multi-Agent Conversation Framework},
  booktitle    = {ArXiv preprint arXiv:2308.08155},
  year         = {2023},
}

Why are these changes needed?

Related issue number

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[JieyuZ2]

please refer to this page for the citation information: https://microsoft.github.io/autogen/docs/Research/

[qingyun-wu]

Closing this PR considering the existence of #43.