README.md: Add DeepWiki badge to Contributing (#4777)

Co-authored-by: RPRX <[email protected]>

README.md

@@ -125,6 +125,8 @@
 
 [Code of Conduct](https://github.com/XTLS/Xray-core/blob/main/CODE_OF_CONDUCT.md)
 
+[![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/XTLS/Xray-core)
+
 ## Credits
 
 - [Xray-core v1.0.0](https://github.com/XTLS/Xray-core/releases/tag/v1.0.0) was forked from [v2fly-core 9a03cc5](https://github.com/v2fly/v2ray-core/commit/9a03cc5c98d04cc28320fcee26dbc236b3291256), and we have made & accumulated a huge number of enhancements over time, check [the release notes for each version](https://github.com/XTLS/Xray-core/releases).