[hpsdr] Penelope clock diasabe- Caution

[Bruce Beford]

Just a word of caution for those who may want to disable the 10 MHz
oscillator on Penelope. Remember that this is a multi-layer board. Use
extreme caution when cutting the 3.3V power trace to U2. Do no go too deep
when cutting. I don't know what the depth of the next layer is. I was able
to carefully cut this power trace with no ill effect. But, be careful if you
decide to do this.

-Bruce N1RX