mention bind commands too

[jidanni]

On man bash _kindly_ mention there is indeed a way to use the following,
with no further ado, by adding the stuff in parentheses:
       dump-functions (bind -P)
              Print all...
       dump-variables (bind -V)
              Print all...
       dump-macros (bind -S)
              Print all...
Otherwise we almost thought we had to make a binding just to run them once.
(Yes, a lawyer could figure out the answers from reading the whole man
page twice.)