Fix path issue for javadoc generation

Author: jonzarling

.github/workflows/doc_generation-6.0.yml

@@ -32,9 +32,10 @@ jobs:
         # Setup gradle and build Java
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@v3
-        
-      - name: Build with Gradle
-        run: ./gradlew build
+      - name: Build with Gradle (and make paths)
+        run: |
+            mkdir -p doc/javadoc
+            ./gradlew build
           
       # generate the javadoc files
       - name: Set up JDK 17