chore(build): auto-generate vimdoc

doc/lazy.nvim.txt

@@ -294,6 +294,15 @@ CONFIGURATION                                        *lazy.nvim-configuration*
           },
         },
       },
+      -- lazy can generate helptags from the headings in markdown readme files,
+      -- so :help works even for plugins that don't have vim docs.
+      -- when the readme opens with :help it will be correctly displayed as markdown
+      readme = {
+        root = vim.fn.stdpath("state") .. "/lazy/readme",
+        files = { "README.md" },
+        -- only generate markdown helptags for plugins that dont have docs
+        skip_if_doc_exists = true,
+      },
     }
 <