Add wiki to artifacts

snapshot the wiki https://github.com/official-stockfish/stockfish/wiki as part of the artifacts generated.
This will allow future release to include the wiki pages as a form of documentation

closes https://github.com/official-stockfish/Stockfish/pull/4420

No functional change

.github/workflows/stockfish_binaries.yml

@@ -83,10 +83,17 @@ jobs:
       - name: Remove non src files
         run: rm -f *.o .depend *.nnue
 
+      - name: Download wiki
+        run: |
+          git clone https://github.com/official-stockfish/Stockfish.wiki.git ../wiki
+          cd ../wiki
+          rm -rf .git
+
       - name: Create tar archive.
         run: |
           cd ..
           mkdir stockfish
+          cp -r wiki stockfish/
           cp -r src stockfish/
           cp stockfish-$OS-$BINARY$EXT stockfish/
           cp "Top CPU Contributors.txt" stockfish/