There should be a section when you create an alliance to post your policies as an alliance so that it is accessible in game for all to see. No need to dig for 3rd party sites. It could be a link on the clan page that takes you to basically a post where the creator of the alliance can post the policies (retal, war, etc...) for anyone to access and see.

I'd like to expand alliances in game at some point; this may be part of that heh

but it's a ways off i think