Mark class support as experimental in the TR docs

Please merge to v6.0.1
(cherry picked from commit d6a3d27e54f778c29e46831b48e63d1f90029d05)
Fix TR reference docs for `for`

Please merge to v6.0.1
(cherry picked from commit e3f7aa4df200bf6250adb02d1ba8c547639960cb)
Minor fix for TR docs for `struct`

Please merge to v6.0.1
(cherry picked from commit 4d7703770f3a2c139091893badb0768044fcb956)