tools: ynl: render event op docs correctly

tools: ynl: render event op docs correctly

The docs for YNL event ops currently render raw python structs. For
example in:

https://docs.kernel.org/netlink/specs/ethtool.html#cable-test-ntf

  event: {‘attributes’: [‘header’, ‘status’, ‘nest’], ‘__lineno__’: 2385}

Handle event ops correctly and render their op attributes:

  event: attributes: [header, status]

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20260112153436.75495-1-donald.hunter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>