feat(config): add left sidebar config for herdr-nvim and update descriptions

dot_config/herdr/config.toml

@@ -108,7 +108,7 @@ description = "navigate right (vim/herdr)"
 key = "prefix+e"
 type = "plugin_action"
 command = "chmarax.herdr-nvim.toggle"
-description = "nvim sidebar"
+description = "nvim sidebar (left of current panes; see ~/.config/herdr-nvim/config.toml)"
 
 [[keys.command]]
 key = "prefix+o"