docs: Introduce an user guide (#1121)

docs/helpers.md

@@ -1,42 +0,0 @@
-# Helpers
-
-Regardless of the way NixVim is used (as a home-manager module, a nixos module, or as a standalone module),
-helpers can be included in the same way.
-
-You can simply use:
-
-```nix
-{
-    helpers,
-    ...
-}: {
-    # Your config
-}
-```
-
-A certain number of helpers are defined that can be useful:
-
-- `helpers.emptyTable`: An empty lua table `{}` that will be included in the final lua configuration.
-  This is equivalent to `{__empty = {};}`. This form can allow to do `option.__empty = {}`.
-
-- `helpers.mkRaw str`: Write the string `str` as raw lua in the final lua configuration.
-  This is equivalent to `{__raw = "lua code";}`. This form can allow to do `option.__raw = "lua code"`.
-
-- `helpers.toLuaObject obj`: Create a string representation of the Nix object. Useful to define your own plugins.
-
-- `helpers.listToUnkeyedAttrs list`: Transforms a list to an "unkeyed" attribute set.
-
-  This allows to define mixed table/list in lua:
-
-  ```nix
-    (listToUnkeyedAttrs ["a", "b"]) // {foo = "bar";}
-  ```
-
-  Resulting in the following lua:
-
-  ```lua
-    {"a", "b", [foo] = "bar"}
-  ```
-
-- `helpers.enableExceptInTests`: Evaluates to `true`, except in `mkTestDerivationFromNixvimModule`
-  where it evaluates to `false`. This allows to skip instantiating plugins that can't be run in tests.