Document whether you can use a name, type, and description with each tag

In jsdoc3/jsdoc#827, @mlippert pointed out that it's not always clear whether a JSDoc tag requires a type. The same is true of the name and description.

In the docs for each tag, we should clearly indicate whether each tag allows a name, type, and/or description. If so, we should indicate whether each value is required or optional.
