Reword 1st part of the dev guide
An attempt to clarify the ideas expressed there.
Could you add a paragraph explaining SRTP? I had no idea it existed when first finding this library, and am still a little unclear about which overload gets chosen with respect to the default1, 2, etc... last arg.
@gusty , it's great that you're enhancing Developer's Guide. I think it will ease the learning curve for new contributors. I have a general sense, that ideas that you're describing are quite abstract, especially for a newcomer. I wonder if we could make it easier by using code examples/snippets. They would obviously have to be quite generic and high-level. But I guess it could be worth it. I think it's a similar case to your blog posts. Topics you've described were highly technical, but you were using code examples and it was easy to follow.
I added more content and tried to address all valuable feedback (thanks @3Rafal , we miss you). If there are no objections I would like to merge it.