Fix "empty input line" warning by groff

Signed-off-by: Sergio Durigan Junior <sergiodj@sergiodj.net>

doc/snac.8

@@ -481,7 +481,6 @@ already exist. I've used this very informative page as a guideline:
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 .Lk https://fedi.tips/transferring-your-mastodon-account-to-another-server/
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-
 1. On the web interface of your origin Mastodon account, click on
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