[docs] Types are missing in the left nav bar of the exported API documentation

[mjameswh]

Describe the bug

In the exported API documentation, structures that are defined with the type keyword appears nowhere in the left nav bar.

For example, ScheduleDescription, which is defined in code as export type ScheduleDescription = { ... } can be navigated from ScheduleHandle.describe, but can't be found directly by searching it in the nav bar.

[mjameswh]

Actually, the same is true of module exported functions, constants and variables. This is due to the way the sidebar is built (i.e. iterating on exported markdown files, but not looking into those files).