docs: add supported architectures section

[MikeMcC399]

• closes Add architecture dependent supportability information #2492

Description

Add a new section "Supported architectures" to the README.md document.

Motivation and Context

The README.md document does not currently describe the support status of the underlying architectures used in the node Docker images.

Debian images (trixie, bookworm & bullseye) all use architectures covered in Node.js Support tiers 1 & 2. These are glibc C library based.

Alpine images rely on musl C library support from nodejs/unofficial-builds that are classified as "Experimental".

node:alpine* images are in wide and successful use since their introduction 10 years ago. Users who choose these images should nevertheless be made aware of the support status of the images. Docker Hub node does not describe support categories.

nodejs/node#62764 seeks to promote Alpine from "Experimental" to "Tier 2" and awareness of the current status may assist in recruiting volunteers to provide additional support and achieve the needed support level promotion.

Testing Details

N/A - documentation change only

Types of changes

• Documentation
• Version change (Update, remove or add more Node.js versions)
• Variant change (Update, remove or add more variants, or versions of variants)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Other (none of the above)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• All new and existing tests passed.

[MikeMcC399]

Preview

https://github.com/MikeMcC399/docker-node/blob/architecture-support/README.md#supported-architectures

[MikeMcC399]

https://github.com/nodejs/node/blob/main/BUILDING.md#platform-list has now been changed to refer explicitly to only Tier 1 & 2:

For production applications, run Node.js on supported platforms only (Tier 1 or 2).

Requested changes from @sxa were implemented

[sxa]

I feel the word "rigourously" in the final sentence about no-x64 platforms is doing a lot of heavy lifting to the point I'd prefer to state that it's explicitly untested or similar as we have no testing at all on that platform at the moment, but I'll approve and let you decide whether to update that :-)

Maybe add a link into the Alpine->tier 2 issue for anyone who would like things to change...

[MikeMcC399]

I feel the word "rigourously" in the final sentence about no-x64 platforms is doing a lot of heavy lifting to the point I'd prefer to state that it's explicitly untested or similar as we have no testing at all on that platform at the moment, but I'll approve and let you decide whether to update that :-)

Agreed, as I've updated this to remove the word.

Maybe add a link into the Alpine->tier 2 issue for anyone who would like things to change...

I'd like to formulate this in a separate PR. Perhaps we could put together a job description concerning tasks, skills, etc.?