acknowledge and provide fix for common error (#2924)

Author: WilliamEspegren

README.md

@@ -106,6 +106,14 @@ Flowise has 3 different modules in a single mono repository.
     pnpm build
     ```
 
+    <details>
+    <summary>Exit code 134 (JavaScript heap out of memory)</summary>  
+      If you get this error when running the above `build` script, try increasing the Node.js heap size and run the script again:
+    
+        export NODE_OPTIONS="--max-old-space-size=4096"
+        pnpm build
+    </details>
+
 5. Start the app:
 
     ```bash