Restore the node 8 remark in readme

Author: nukeop

node/README.md

@@ -1,6 +1,7 @@
 # flatpak-node-generator
 
-A more modern successor for flatpak-npm-generator and flatpak-yarn-generator. Supports npm, yarn, and pnpm.
+A more modern successor for flatpak-npm-generator and flatpak-yarn-generator, for Node 10+ only. Supports npm, yarn, and pnpm.
+(For Node 8, use flatpak-npm-generator and flatpak-yarn-generator.)
 
 **NOTE:** `--xdg-layout` was recently changed to be the default. In the stark
 majority of cases, this needed to be passed, so you can now omit using it