Added a paragraph about the clearpassphrases script.
Added a paragraph about the clearpassphrases script.

ahelsing/geni-tools,GENI-NSF/gram,plantigrade/geni-tools,ahelsing/geni-tools,GENI-NSF/gram,GENI-NSF/gram,plantigrade/geni-tools,tcmitchell/geni-tools,tcmitchell/geni-tools