docs/tools/virtiofsd.rst: Delete stray backtick

The documentation of the posix_acl option has a stray backtick
at the end of the text (which is rendered literally into the HTML).
Delete it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-id: 20210726142338.31872-11-peter.maydell@linaro.org

docs/tools/virtiofsd.rst

@@ -102,7 +102,7 @@ Options
     default is ``no_xattr``.
 
   * posix_acl|no_posix_acl -
-    Enable/disable posix acl support.  Posix ACLs are disabled by default`.
+    Enable/disable posix acl support.  Posix ACLs are disabled by default.
 
 .. option:: --socket-path=PATH