README.md: update links to go.dev
README.md: update links to go.dev

Fixes #50916.

Change-Id: I51f3269b7a0793a3002eef83de1d871111fc3cdc
GitHub-Last-Rev: fc8c183ac7fa84d6caefdf49ed1d8cac19d7744f
GitHub-Pull-Request: golang/go#50919
Reviewed-on: https://go-review.googlesource.com/c/go/+/381962
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Trust: Cherry Mui <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
Reviewed-by: Daniel Martí <29bf28b42a938ace12a5819da4ed4ba03d82f315@mvdan.cc>
Trust: Daniel Martí <29bf28b42a938ace12a5819da4ed4ba03d82f315@mvdan.cc>

nawawi/go,CAFxX/go,golang/go,nawawi/go,nawawi/go,golang/go,CAFxX/go,nawawi/go,CAFxX/go,CAFxX/go,nawawi/go,golang/go,CAFxX/go,nawawi/go,nawawi/go,CAFxX/go,CAFxX/go,golang/go,golang/go,golang/go,golang/go,CAFxX/go,golang/go,nawawi/go