Try another workaround to build docs

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

Author: mxpv

.github/workflows/docs.yml

@@ -31,11 +31,13 @@ jobs:
         version: 0.14.1
 
     # I don't know why this is needed for the docs to succeed on CI, but otherwise it consistently fails with:
-    #   error: unable to open directory '.zig-cache/b/': FileNotFound
+    #   error: unable to open directory '...': FileNotFound
     # See https://github.com/mxpv/luaz/actions/runs/16698403816/job/47265761593
-    - run: zig build
-
-    - run: zig build docs
+    - run: |
+        mkdir -p ./.zig-global-cache
+        zig build docs
+      env:
+        ZIG_GLOBAL_CACHE_DIR: ./.zig-global-cache
 
     - uses: actions/configure-pages@v5
     - uses: actions/upload-pages-artifact@v3