Add DeepWiki badge to README (calcom#28679)

Added a badge for DeepWiki to the README.

Author: kayareyouokay

README.md

@@ -27,6 +27,7 @@
    <img src="https://api.checklyhq.com/v1/badges/groups/1120718?style=flat&theme=default" alt="Checkly QA">
    <a href="https://status.cal.com"><img height="20px" src="https://betteruptime.com/status-badges/v1/monitor/a9kf.svg" alt="Uptime"></a>
    <a href="https://github.com/calcom/cal.com/stargazers"><img src="https://img.shields.io/github/stars/calcom/cal.com" alt="Github Stars"></a>
+   <a href="https://deepwiki.com/calcom/cal.com"><img src="https://deepwiki.com/badge.svg" alt="Ask DeepWiki"></a>
    <a href="https://news.ycombinator.com/item?id=34507672"><img src="https://img.shields.io/badge/Hacker%20News-%231-%23FF6600" alt="Hacker News"></a>
    <a href="https://github.com/calcom/cal.com/blob/main/LICENSE"><img src="https://img.shields.io/badge/license-AGPLv3-purple" alt="License"></a>
    <a href="https://github.com/calcom/cal.com/pulse"><img src="https://img.shields.io/github/commit-activity/m/calcom/cal.com" alt="Commits-per-month"></a>