Add vimtext plugin.

config/nvim/lua/plugins/vimtext.lua

@@ -0,0 +1,9 @@
+return {
+  'lervag/vimtex',
+  lazy = false, -- we don't want to lazy load VimTeX
+  -- tag = "v2.15", -- uncomment to pin to a specific release
+  init = function()
+    -- VimTeX configuration goes here, e.g.
+    vim.g.vimtex_view_method = 'zathura'
+  end,
+}