meta: add more information about nightly releases

PR-URL: https://github.com/nodejs/node/pull/55084
Reviewed-By: Vinícius Lourenço Claro Cardoso <contact@viniciusl.com.br>
Reviewed-By: Jake Yuesong Li <jake.yuesong@gmail.com>

README.md

@@ -81,8 +81,10 @@ directory contains the latest Hydrogen (Node.js 18) release.
 
 <https://nodejs.org/download/nightly/>
 
-Each directory name and filename contains a date (in UTC) and the commit
-SHA at the HEAD of the release.
+Each directory and filename includes the version (e.g., `v22.0.0`),
+followed by the UTC date (e.g., `20240424` for April 24, 2024),
+and the short commit SHA of the HEAD of the release (e.g., `ddd0a9e494`).
+For instance, a full directory name might look like `v22.0.0-nightly20240424ddd0a9e494`.
 
 #### API documentation