message: docs: Fix refs in Lua docs
  This is a docs only change, mostly on how to refer to LuaPerRoute info.
diff: @@ -111,7 +111,8 @@ As a concrete example, given the following Lua filter configuration:
  end
  The HTTP Lua filter can be disabled on some virtual host, route, or weighted cluster by the
  -LuaPerRoute configuration as follow:
  +:ref:`LuaPerRoute <envoy_v3_api_msg_extensions.filters.http.lua.v3.LuaPerRoute>` configuration as
  +follow:
  .. code-block:: yaml
  