added toggleterm.nvim

nix/users/base/neovim/plugins/toggleterm.lua

@@ -0,0 +1,10 @@
+local status, plugin = pcall(require,'toggleterm')
+if not status then
+    print('Error with plugin: ', plugin)
+    return
+end
+plugin.setup({
+    size = 10,
+    open_mapping = [[<c-\>]],
+    direction = 'horizontal',
+})