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.
What is the reason for adding "a value of" here?  The original wording seems more direct and both wordings seem equally unambiguous.  (Note: I'd like to replace that big ugly illustration at some point, so there will be opportunity for rephrasing later.)