Add automatic retry for markdown link validation step

Co-authored-by: sjdemartini <[email protected]>

Author: Copilot

.github/workflows/build-test.yml

@@ -177,7 +177,13 @@ jobs:
         # README and documentation is updated, we want to ensure that links
         # remain correct. (This also checks external links, though that's a
         # secondary concern.)
-        run: pnpm run md-link:check
+        # Use retry action to automatically retry once if the check fails due to
+        # transient network issues or other flakiness.
+        uses: nick-fields/retry@v3
+        with:
+          max_attempts: 2
+          timeout_minutes: 5
+          command: pnpm run md-link:check
 
       - name: Test
         # Run the tests and print out the coverage information. In the future,