personal-keybindings: add docstring

fix typo in bind-key docstring
bind-key: no vector keys in personal-keybindings

describe-personal-keybindings requires the key sequences to be stored as
strings.
bind-key: cleanup
Merge pull request #110 from npostavs/desc-vector

Avoid putting vector key sequences in personal-keybindings
bind-keys macro changed to allow prefix map to have a menu string.
Merge pull request #112 from BernardHurley/master

bind-keys macro changed to allow prefix map to have a menu string.