all: announce end of support for old Linux versions

[dmitshur]

New Linux versions get released over time, and old ones cannot be supported indefinitely. This is the tracking recurring issue for announcing end of support for very old versions that we decide to drop support for. (The corresponding tracking issues for macOS and Windows, the other two OSes that have first class ports, are #23011 and #52188.)

The most recent change was applied in Go 1.18, where proposal #45964 increased the minimum Linux kernel version requirement from 2.6.23 to 2.6.32. See https://go.dev/doc/go1.18#linux.

CC @golang/release.

[ianlancetaylor]

Just a note that the case for Linux is a bit different than that for macOS and Windows, as Linux does not have a sole vendor. We need to identify organizations that distribute older versions of Linux that are supported and used. For example, I believe that we should continue to support all versions of Linux that are actively supported by commercial organizations, such as RHEL or Suse Linux Enterprise Server, and also all versions of Linux that are actively supported by communities supporting stable versions, such as Rocky Linux. Of course the nature of Linux is such that the set of active organizations changes over time.