Add architecture dependent supportability information

[MikeMcC399]

Situation

The README document does not contain information about the supportability of image variants. This can lead to a mismatch of user expectations versus actual supportability.

Suggestion

Add architecture dependent supportability information to the README document based on existing documents.

Architecture builds

versions.json

Platform list

Node.js provides information in the Building Node.js document, Platform list table. Platforms may move between tiers between major release lines:

• v22.x
• v24.x
• v25.x
• v26.x

Architectures

glibc

All architectures using glibc are either Tier 1 or Tier 2 supported:

Docker	Node.js	Version	OS	Node.js 22	Node.js 24	Node.js 25	Node.js 26
amd64	x64	glibc	Debian	Tier 1	Tier 1	Tier 1	Tier 1
arm32v7	armv7	glibc	Debian	Tier 1	-	-	-
arm64v8	arm64	glibc	Debian	Tier 1	Tier 1	Tier 1	Tier 1
ppc64le	ppc64le	glibc	Debian	Tier 2	Tier 2	Tier 2	Tier 2
s390x	s390x	glibc	Debian	Tier 2	Tier 2	Tier 2	Tier 2

musl

• The Node.js Platform list table lists only x64 / musl and displays this architecture combination under "Experimental" support type
• The Unofficial builds repo explicitly lists only linux-x64-musl and linux-arm64-musl

Docker	Node.js	Version	OS	Node.js 22	Node.js 24	Node.js 25	Node.js 26
amd64	x64	musl	Alpine	Experimental	Experimental	Experimental	Experimental
arm32v6	armv6	musl	Alpine	?	-	-	-
arm32v7	armv7	musl	Alpine	?	-	-	-
arm64v8	arm64	musl	Alpine	Experimental	Experimental	Experimental	Experimental
s390x	s390x	musl	Alpine	?	?	?	-

The support levels for armv6, armv7 and s390x are not explicitly documented.

Docker images built by cross-platform building for Alpine, based on musl builds from Unofficial builds are at most "Experimental" and for armv6, armv7 and s390x should possibly be considered as unsupported.

Experimental architectures are not recommended for use with production applications.

Unsupported architectures, by implication, are also not recommended for use with production applications.

Debian architectures

Debian reduces supported architectures when releases transition from End-of-Life to LTS

Debian 11 (bullseye) supports i386, amd64, armhf and arm64