Link to syscall.md

Author: ringtailsoftware

README.md

@@ -167,7 +167,7 @@ The best source of information is the header file [uvm32/uvm32.h](uvm32/uvm32.h)
 
 A test coverage report is generated by running `make test` and is attached to each automated build.
 
-Also see [doc/README.md](doc/README.md)
+Also see [doc/README.md](doc/README.md) and [doc/syscall.md](doc/syscall.md)
 
 ## License