Enhance doc-check workflow with artifact upload

Added an upload artifact step to the documentation check workflow.

Author: vasac

.github/workflows/doc-check.yaml

@@ -68,6 +68,12 @@ jobs:
     - name: Documentation Link Check
       shell: bash
       run: |
-        make clean
         make build-operator
         make test-docs
+
+    - name: Upload artifact
+      uses: actions/upload-artifact@v4
+      with:
+          name: build-output
+          path: coherence-operator/build/_output/*
+          retention-days: 7