code: public Changes parameter(String name, String value) {
          this.databaseHelper.query(name, value);
          return this;
      }
docs: Add a custom query parameter to the _changes request. Useful for specifying extra parameters
  to a filter function for example.
  
  @param name  the name of the query parameter
  @param value the value of the query parameter
  @return this Changes instance
  @since 2.5.0