docs readme: added mascot picture

Signed-off-by: Makise Kurisu <1354965069@qq.com>

Author: asdqweszq

README.md

@@ -4,7 +4,7 @@
 
 bfdev is a high-performance, aesthetically pleasing, and portable infrastructure provisioning library. Its goal is to provide a comprehensive and streamlined development environment.
 
-![logo](docs/images/logo.png)
+![mascot](docs/images/mascot.jpg)
 
 ## Continuous Integration Status