Description
Currently the 'hide'/'move to sidebar' buttons in pinnable elements dont provide any context to screenreader users on what is being hidden or moved, its possible to have multiple buttons with the same label.
Instead we should use 'aria-label' on those buttons to read out 'Hide table of contents' or 'Move table of contents to sidebar'.
AC
- 'hide'/'move to sidebar' buttons have accessible labels that describe the element being hidden/moved
- no visual changes
