Add a note clarifying Node.js upgrade strat (#1849)

Co-authored-by: Chris Swithinbank <[email protected]>
Co-authored-by: Erika <[email protected]>

Author: 3 people

src/content/blog/astro-580.mdx

@@ -39,6 +39,10 @@ yarn upgrade astro --latest
 
 ## Updated minimum Node.js version to 18.20.8
 
+<Note title="Edit (2025-09-26)">
+Fred here! In retrospect, this explanation is pretty confusing. To be clear: Astro 5 supports Node.js v18 LTS and will continue to support it until our next major release sometime in the future, Astro 6.0. We only drop support for LTS major versions of Node.js in major version releases of Astro. Our documented [Node.js support policy](https://docs.astro.build/en/upgrade-astro/#upgrade) has the full details.
+</Note>
+
 Node.js 18 has now reached end-of-life and will no longer receive security updates or support. Therefore, Astro 5.8 now requires v20.3.0, v22.0.0 or higher. (v19 and v21 are not supported.) To help users upgrade, Astro will temporarily continue to support Node.js 18.20.8, which is the final LTS release of Node.js 18.
 
 We will drop support for Node.js 18 entirely in a future release, so we recommend upgrading to Node.js 22 as soon as possible. See Astro's [Node.js support policy](https://docs.astro.build/en/upgrade-astro/#nodejs-support-and-upgrade-policies) for more details about how and when we upgrade the minimum Maintenance LTS version.