add autocmds configuration

- create autocmds.nix for custom autocommands
- integrate autocmds into main configuration

config/autocmds.nix

@@ -0,0 +1,8 @@
+{...}: {
+  config.autoCmd = [
+    { # Balance splits when our teminal resizes
+      command = "wincmd =";
+      event = [ "VimResized" ];
+    }
+  ];
+}

config/default.nix

@@ -1,6 +1,7 @@
 {...}: {
   imports = [
     # General Configuration
+    ./autocmds.nix
     ./keymaps.nix
     ./options.nix