"std API docs" should be relabeled on the homepage

For a while it has been possible to search and access all of the builtin crate API docs from "std API docs".  Since I think 'all API docs' is usually what people want, and the current labeling suggests you need to click "All docs" (which goes to another page listing all forms of documentation) to get that, the link text should be changed to "API docs" or something.
