ref: Code refactoring

- Try to not expose as much commands and code via neogen
- Use minidoc to generate docgen

scripts/minidoc.lua

@@ -0,0 +1,7 @@
+local minidoc = require("mini.doc")
+
+if _G.MiniDoc == nil then
+    minidoc.setup()
+end
+
+minidoc.generate({ "lua/neogen/init.lua" }, nil, nil)