[docs][docs infra] confusing side nav behavior

[angelinalg]

Description

When I'm in the Ray Train > Ray Train API sub-directory of the LHS nav, and I collapse the Ray Train API level, I expect to stay in the Ray Train level. However, I am popped into the Ray Data level. This is disorienting.
cc: @emmyscode

Screen.Recording.2023-09-28.at.3.58.53.PM.mov

Link

No response

[peytondmurray]

Fixed by #41115.