Consider displaying accessors (`Attributes`) in sidebar or merging with Instance Methods

[adam12]

Certain classes contain a collection of useful instance methods that become less visible due to their status as accessors, leading to their omission from the sidebar.

For instance, Net::HTTP includes various configuration options for the SSL context, such as ca_cert, cert, and key. However, these options are located towards the bottom of the main viewport, making them less easily discoverable.

Listing them in the sidebar would enhance their visibility and accessibility.

[st0012]

Though attributes function the same as normal methods, they capture more context about the intention. And IMO that context should be captured in documentation, so they should NOT be treated as normal methods by RDoc.
I lean towards listing attributes in the sidebar too, but I'd wait a bit to see what others think before making a PR.