API docs: sidebar: clicking "Constants", "Variables", etc. behave as buttons

Created by: slimsag

Previously, the dropdown button and Constants text in > Constants were two seperate functions: one expands the area, the other jumps to the "Constants" section of the page. This is a bit confusing, though, because jumping to the section of the page also means it gets automatically expanded. This makes some users think clicking the text makes the area expand, which is not true.

So, make clicking on "Constants", "Variables", etc. do what the user expects: expand/collapse.

The only caveat to this is that some expandable sections, like type Foo struct with methods below it, will continue to act as having two seperate buttons.

Signed-off-by: Stephen Gutekanst [email protected]