doc: Fix git-send-email example

git-send-email lacks --body option.

Fixes: 4a72aad ("New LTP documentation")
Closes: #1284
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Ricardo Branco <rbranco@suse.de>

Author: ricardobranco777

doc/developers/setup_mailinglist.rst

@@ -27,7 +27,7 @@ To test the configuration you can use ``--dry-run`` parameter.
 
 .. code-block:: bash
 
-    git send-email --dry-run --to "ltp@lists.linux.it" --subject "Test Email" --body "This is a test email." HEAD^
+    git send-email --dry-run --to "ltp@lists.linux.it" --subject "Test Email" HEAD^
 
 Depending on your SMTP server's configuration, you may need to authenticate
 before sending emails. If required, configure authentication settings using: