doc: change erroneous --[no]-whatever into --[no-]whatever

Change these two obvious typos to be in line with the rest of the
documentation, which uses the correct --[no-]whatever form.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-format-patch.txt

@@ -239,7 +239,7 @@ keeping them as Git notes allows them to be maintained between versions
 of the patch series (but see the discussion of the `notes.rewrite`
 configuration options in linkgit:git-notes[1] to use this workflow).
 
---[no]-signature=<signature>::
+--[no-]signature=<signature>::
 	Add a signature to each message produced. Per RFC 3676 the signature
 	is separated from the body by a line with '-- ' on it. If the
 	signature option is omitted the signature defaults to the Git version

Documentation/git-send-email.txt

@@ -89,7 +89,7 @@ See the CONFIGURATION section for `sendemail.multiEdit`.
 	reply to the given Message-Id, which avoids breaking threads to
 	provide a new patch series.
 	The second and subsequent emails will be sent as replies according to
-	the `--[no]-chain-reply-to` setting.
+	the `--[no-]chain-reply-to` setting.
 +
 So for example when `--thread` and `--no-chain-reply-to` are specified, the
 second and subsequent patches will be replies to the first one like in the