Add maintainer for VxWorks

Author: hax0kartik

src/doc/rustc/src/platform-support/vxworks.md

@@ -20,6 +20,7 @@ Target triplets available:
 ## Target maintainers
 
 [@biabbas](https://github.com/biabbas)
+[@hax0kartik](https://github.com/hax0kartik)
 
 ## Requirements