spec: TI5 Clarify when a URL should be appended to log messages

[mattheworiordan]

Rather belated, but here's my attempt at clarifying when a URL is included in log entries shown to users. Specifically addressing ably/ably-ruby#171 (comment) and ably/ably-ruby@ea425be.

[paddybyers]

Is it worth clarifying what we mean by "If the URL is not already present within the contents of the @message@ attribute ..."

The implementation in Ruby determines what the URL should be, based on the href and/or code, and then looks for that exact URL in the message, appending the URL if that isn't found.

I think this text should make it clear that the "If the URL is not already present .." check requires an exact match, or we should perhaps specify some more relaxed match if we think that's appropriate.
Should we ma

[SimonWoolf]

given that the 'not already present' requirement is only temporary (we can remove it in the 1.1 spec, since for v=1.1 realtime doesn't append an href to the message, so it's only really applicable for particularly keen client libs that want to implement this spec item before 1.1), probably not worth being too particular about it

[mattheworiordan]

probably not worth being too particular about it

I'd be happy with that 👍