docgen: Generate a tar file for the doc artifact

A tar.xz file is easier to deal with that a zip file containing a tar
file.

Signed-off-by: David Brown <[email protected]>

.github/workflows/docs.yml

@@ -67,10 +67,16 @@ jobs:
           cargo doc
           mv target/doc ../docout/std
 
-      - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+      - name: compress-docs
+        working-directory: zephyr-rust-lang
+        run: |
+          tar --use-compress-program="xz -T0" -cf rust-lang-html.tar.xz docout
+
+      - name: Upload build
+        uses: actions/upload-artifact@v4
         with:
-          path: zephyr-rust-lang/docout
+          name: rust-lang-html
+          path: zephyr-rust-lang/rust-lang-html.tar.xz
 
   deploy:
     needs: generate-docs