..otherwise it looks like combinations of args are optional rather than individual args.

- fix broken link for version example
- make all links more specific

Some return values of the callbacks weren't correctly indented, which
made things unpleasant to read.

If `x` has a property explicitly set to `undefined` then `expect(x).to.eql(y)` requires `y` to also have a property set to undefined. This PR relaxes that requirement to also allow `y` to simply not have the property.

This is to save having to explicitly re-define this property to undefined when y has been `JSON.stringify`'d. This happens in the ipfs-postmsg-proxy and this change removes the need for the proxy to know the shape of this object (or at least which properties might have been undefined).

License: MIT
Signed-off-by: Alan Shaw <alan.shaw@protocol.ai>

Previously this test was using the default options so we weren't able to tell if the output was correct when given options that weren't the defaults!

License: MIT
Signed-off-by: Alan Shaw <alan.shaw@protocol.ai>