doc: clarify Linux runtime requirements for >=25

Due to the switch to Clang on Linux for building the official
releases, the binaries now require libatomic to run.

Author: joyeecheung

BUILDING.md

@@ -175,6 +175,11 @@ Binaries at <https://nodejs.org/download/release/> are produced on:
 | win-arm64               | Windows Server 2022 (x64) with Visual Studio 2022             |
 | win-x64                 | Windows Server 2022 (x64) with Visual Studio 2022             |
 
+Starting with Node.js 25, official Linux binaries are linked with `libatomic` and these systems
+must have the `libatomic` runtime installed and available at execution time to run the binaries.
+The package name for the `libatomic` runtime is typically `libatomic` or `libatomic1` depending
+on your Linux distibution
+
 <!--lint disable final-definition-->
 
 [^5]: Binaries produced on these systems require libstdc++12, available