code: public K3poRule addScriptRoot(String shortName, String packagePath) {
          packagePathsByName.put(shortName, packagePath);
          return this;
      }
docs: Adds a named ClassPath root of where to look for scripts when resolving them.
  Specifications should reference the short name using {@code "${shortName}/..." } in script names.
  
  @param shortName  the short name used to refer to the package path
  @param packagePath a package path used resolve relative script names
  
  @return an instance of K3poRule for convenience