set_freq documentation issue #60

The header for the set_freq method is as follows:

/*

• set_freq(uint64_t freq, enum si5351_clock clk)
• Sets the clock frequency of the specified CLK output.
• Frequency range of 8 kHz to 150 MHz
• freq - Output frequency in Hz
• clk - Clock output
• (use the si5351_clock enum)
  */
  uint8_t Si5351::set_freq(uint64_t freq, enum si5351_clock clk)

Specifically it says that the 'freq' is the output frequency in Herz. This is incorrect. The value of the parameter should be given in units of 0.01 Herz.