update the release buck2 version in doc (#2034)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/2034

buck2 and prelude are updated in D53878006. If users rely on an old buck2 binary, oss buck build won't work anymore

Reviewed By: tarun292, huydhn

Differential Revision: D54038266

fbshipit-source-id: fce9d4058f189c34894d23ba45d78df56b4a5f6f