docs: Add an FAQ entry for keymap aliases (#1301)

Fixes #1215

docs/user-guide/faq.md

@@ -45,3 +45,45 @@ When using NixVim it is possible to encounter an error of the type `attribute 'n
 This usually means one of two things:
 - The nixpkgs version is not in line with NixVim (for example nixpkgs nixos-23.11 is used with NixVim master)
 - The nixpkgs unstable version used with NixVim is not recent enough.
+
+## How do I create multiple aliases for a single keymap
+
+You could use the builtin [`map`] function (or similar) to do something like this:
+
+```nix
+keymaps =
+  (builtins.map (key: {
+    inherit key;
+    action = "<some-action>";
+    options.desc = "My cool keymapping";
+  }) ["<key-1>" "<key-2>" "<key-3>"])
+  ++ [
+    # Other keymaps...
+  ];
+```
+
+This maps a list of keys into a list of similar [`keymaps`]. It is equivalent to:
+
+```nix
+keymaps = [
+  {
+    key = "<key-1>";
+    action = "<some-action>";
+    options.desc = "My cool keymapping";
+  }
+  {
+    key = "<key-2>";
+    action = "<some-action>";
+    options.desc = "My cool keymapping";
+  }
+  {
+    key = "<key-3>";
+    action = "<some-action>";
+    options.desc = "My cool keymapping";
+  }
+  # Other keymaps...
+];
+```
+
+[`map`]: https://nixos.org/manual/nix/stable/language/builtins#builtins-map
+[`keymaps`]: ../keymaps