feat(nvim): add and start configuring zen-mode

Fixes: #21

roles/neovim/files/after/plugin/twilight.lua

@@ -0,0 +1,8 @@
+local status_ok, twilight = pcall(require, "twilight")
+if not status_ok then
+  return
+end
+
+twilight.setup {
+  context = 2,
+}

roles/neovim/files/after/plugin/zen-mode.lua

@@ -0,0 +1,25 @@
+local status_ok, zen_mode = pcall(require, "zen-mode")
+if not status_ok then
+  return
+end
+
+zen_mode.setup {
+  window = {
+    backdrop = .95,
+    height = 1,
+    width = 120,
+    options = {
+      relativenumber = false,
+      number = false,
+      signcolumn = "no",
+    }
+  },
+  plugins = {
+    options = {
+      enabled = true,
+      ruler = false,
+    },
+    gitsigns = { enabled = true },
+    tmux = { enabled = true },
+  }
+}