[docs] [issue39654] pyclbr: remove old references to class browser & add explain readmodule

New submission from Batuhan Taskaya <batuhanosmantaskaya@gmail.com>: This is something revealed during issue 39411. As @terry.reedy commented pyclbr's scope is extended to functions and classes instead of just classes. ---------- nosy: +BTaskaya, terry.reedy _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue39654> _______________________________________