add artifact capture to docs action

.github/workflows/docs.yml

@@ -13,4 +13,7 @@ jobs:
                 apt install sudo -y 
             - uses: cachix/install-nix-action@v27
             - name: Build package from flake
-              run: nix build .#docs
+              run: nix build .#docs
+            - uses: actions/upload-artifact@v7
+              with:
+                path: ./result