fix: Add xref content to name when format is none

This change adds `xref` content to `name` when the `format="none"` in
`xref` element.

Fixes #683

xml2rfc/writers/html.py

@@ -2844,6 +2844,8 @@ def render_xref(self, h, x):
                 target = id_for_pn(target)
             # plain xref
             if in_name:
+                if format == 'none':
+                    reftext = content
                 hh = build.em('[', reftext, ']', classes='xref cite')
             else:
                 srefclass = 'xref internal'