vim: remove keymap for listing and switching buffers

This functionality has been replaced with `<leader>fb`, which used
Telescope to fuzzy find open buffers. This is much better because the
list of buffers is more readable and Telescope supports live preview of
the contents before switching.

config/nvim/lua/fs/keymaps.lua

@@ -51,9 +51,6 @@ nmap { '<leader>lr', '<cmd>set number relativenumber<CR>'     , { silent = true
 -- show/hide listchars
 nmap { '<leader>sl', '<cmd>set list!<CR>', { silent = true } }
 
--- show list of buffers and prepare to switch
-nmap { '<leader>bf', '<cmd>ls<CR>:b<Space>' }
-
 -- quickly change background
 nmap { '<leader>bg', [[<cmd>let &background = &background ==? 'light' ? 'dark' : 'light'<cr>]] }