docs: user-guide/helpers.md → lib/index.md

Move the user-guide to the new lib reference docs.

Added a MDBook redirect entry.

Updated man docs.

docs/lib/pages.nix

@@ -4,5 +4,9 @@
 # If there is an issue parsing the file, the resulting markdown will not contain any function docs.
 
 {
-  # TODO
+  lib.pages = {
+    nixvim = {
+      markdown = ./index.md;
+    };
+  };
 }