Fix encryption warning "read more" link (#39635)

app/javascript/mastodon/features/compose/components/warning.tsx

@@ -62,7 +62,11 @@ export const Warning = () => {
           id='compose_form.encryption_warning'
           defaultMessage='Posts on Mastodon are not end-to-end encrypted. Do not share any dangerous information over Mastodon.'
         />{' '}
-        <a href='/terms' target='_blank'>
+        <a
+          href='https://docs.joinmastodon.org/user/posting/#private'
+          rel='noreferrer'
+          target='_blank'
+        >
           <FormattedMessage
             id='compose_form.direct_message_warning_learn_more'
             defaultMessage='Learn more'