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.
Perhaps, but many other people use "orphan" and "orphan block" to refer to blocks no longer on the best chain.  It would be nice if people expecting those terms could search the page and be taken to the location where we explain what term we use.