golang-1.21-doc binary package in Ubuntu Mantic amd64

 The Go programming language is an open source project to make
 programmers more productive. Go is expressive, concise, clean, and
 efficient. Its concurrency mechanisms make it easy to write programs
 that get the most out of multicore and networked machines, while its
 novel type system enables flexible and modular program construction.
 Go compiles quickly to machine code yet has the convenience of
 garbage collection and the power of run-time reflection. It's a fast,
 statically typed, compiled language that feels like a dynamically
 typed, interpreted language.
 .
 This package provides the documentation for the Go programming
 language.

Source package