fix(): missing comma in Lua config (#1)

The missing comma causes the error `E5107: Error loading lua [string ":lua"]:15: '}' expected (to close '{' at line 4) near 'lsp'` when opening neovim.

README.md

@@ -41,7 +41,7 @@ require("flutter-tools").setup {
   },
   outline = {
     open_cmd = "30vnew",
-  }
+  },
   lsp = {
     on_attach = my_custom_on_attach,
     capabilities = my_custom_capabilities -- e.g. lsp_status capabilities