Add cocumentation to ScattererConfiguration comparison operator

   * for dimensions).

   * \param dc_matrix: Matrix of reference dielectric constants.

   * \param has_external: `bool` Flag to set whether to add an external spherical layer.

   * \param exdc: `double` EXDC

   * \param exdc: `double` External medium dielectric constant.

   * \param wp: `double` wp

   * \param xip: `double` xip

   */

  void write_formatted(std::string file_name);

  /*! \brief Test whether two instances of ScattererConfiguration are equal.

   *

   * ScattererConfiguration objects can be obtained in a variety of manner. They can

   * be constructed manually, through the class constructor, they can be read from

   * formatted configuration files, or they can be loaded from binary files. The `==`

   * operator tests for the equivalence of two configuration instances, returning `true`

   * if they are equivalnet, `false` otherwise.

   *

   * \param other: `ScattererConfiguration &` Reference to the instance to be compared with.

   * \return result: `bool` True, if the two instances are equal, false otherwise.