Update package.yml.md with correct sourceforge info

The link for hplip was misspelled using "projects" instead of "project"
Correct instances of "projects" to "project"

docs/packaging/package.yml.md

@@ -77,9 +77,9 @@ Not all fields in `package.yml` are mandatory, but a small selection are. Below
   - Example: `https://github.com/docker/cli/archive/refs/tags/v25.0.3.tar.gz#docker-cli.tar.gz : 04ad0cea992a65db20cb1b0dbf6d1ce32c705ce879de51b22095fe8d28030815`
   - This renames the downloaded file from `v25.0.3.tar.gz` to `docker-cli.tar.gz`.
 - SourceForge sources
-  - A proper SourceForge source looks like this, using `hplip` as an example: `https://sourceforge.net/projects/hplip/files/hplip/3.23.12/hplip-3.23.12.tar.gz`
+  - A proper SourceForge source looks like this, using `hplip` as an example: `https://downloads.sourceforge.net/project/hplip/hplip/3.24.4/hplip-3.24.4.tar.gz`
     - This URL begins with `https://sourceforge.net/`, not `https://downloads.sourceforge.net/`, or some other mirror.
-    - This URL has a path beginning with `/projects/$project_name/`
+    - This URL has a path beginning with `/project/$project_name/`
     - This URL does _not_ have a trailing `/download`, you may have to remove this by hand.
   - The correct SourceForge tarball URLs are found under the "Files" tab, then often within a directory, when starting from a project homepage on SourceForge.