feat(erlang): add Erlang language (#3911)

I usually work with Elixir codebases, but sometimes I want to browse and
code with Erlang codebases, so here is the config I've been using for
Erlang.

lua/lazyvim/plugins/extras/lang/erlang.lua

@@ -0,0 +1,20 @@
+return {
+  recommended = function()
+    return LazyVim.extras.wants({
+      ft = { "erlang" },
+      root = { "rebar.config", "erlang.mk" },
+    })
+  end,
+  {
+    "neovim/nvim-lspconfig",
+    opts = {
+      servers = {
+        erlangls = {},
+      },
+    },
+  },
+  {
+    "nvim-treesitter/nvim-treesitter",
+    opts = { ensure_installed = { "erlang" } },
+  },
+}