README: use syntax highlighing (#41)

Author: kolyshkin

README.md

@@ -1,7 +1,7 @@
 # go-rpmdb
 Library for enumerating packages in an RPM DB `Packages` file (without bindings).
 
-```
+```go
 package main
 
 import (
@@ -36,4 +36,4 @@ func run() error {
 	fmt.Printf("[Total Packages: %d]\n", len(pkgList))
 	return nil
 }
-```
+```