doc: remove list of versions in BUILDING.md

Author: aduh95

BUILDING.md

@@ -226,12 +226,11 @@ If compiling without one of the above, use `configure` with the
 ### Previous versions of this document
 
 Supported platforms and toolchains change with each major version of Node.js.
-This document is only valid for the current major version of Node.js.
-Consult previous versions of this document for older versions of Node.js:
+This document is only valid for the current version of Node.js, and is expected
+to be valid for the entire lifetime of this release line.
 
-* [Node.js 24](https://github.com/nodejs/node/blob/v24.x/BUILDING.md)
-* [Node.js 22](https://github.com/nodejs/node/blob/v22.x/BUILDING.md)
-* [Node.js 20](https://github.com/nodejs/node/blob/v20.x/BUILDING.md)
+To consult the version of this document for another version, download its source
+tarball and/or browse the git repository checked out at the relevant tag.
 
 ## Building Node.js on supported platforms