DevDocs corrections part 1

Started reviewing the developer docs, finding lots of things to correct. I'll do more later, but please review this batch first so I know what, if anything, needs to be fixed moving forward - I'm not entirely sure on the markdownish format used.
Sure, but a bitcoin is also a specific unit of value.  In the discussion linked to above we tried to find a term for generic value which had no unwanted connotations, but we failed.  In the end, we decided that we'd either have to use "bitcoin" or "satoshi", and so we (basically) flipped a coin and "satoshi" won.

I'd prefer to stick with the previous decision rather than update all the text and illustrations.