[i18n] some mistake in imp/locale/en_US/help.xml

[David Chang]

Hi all:
I think that some words should be correct in imp/locale/en_US/help.xml (head)
there are:
line 415
 org:
 <heading>Name</heading>
 should be:
 <heading>Passphrase</heading>

line 425
 org:
 Create and store your personal/private keypair.
 should be:
 Create and store your personal public/private keypair.

David