Update README with #275 QNAP ZFS issue info

README.md

@@ -55,6 +55,7 @@ Valheim Server in a Docker Container (with [BepInEx](#bepinexpack-valheim) and [
 * [QNAP NAS Help](#qnap-nas-help)
 	* [Creating container](#creating-container)
 	* [Updating image](#updating-image)
+	* [QNAP ZFS info](#qnap-zfs-info)
 * [License](#license)
 * [Legal disclaimer](#legal-disclaimer)
 <!-- vim-markdown-toc -->
@@ -792,6 +793,19 @@ After the image is downloaded restart the container. As you can see the old imag
 
 ![Qnap update Step 4](https://raw.githubusercontent.com/lloesche/valheim-server-docker/main/misc/qnap_update_images.png "Qnap update Step 4")
 
+
+## QNAP ZFS issue
+We have had [a report from a QNAP user](https://github.com/lloesche/valheim-server-docker/issues/275) where Steam failed when using ZFS as the backing filesystem with the following error
+```
+valheim-updater [ 0%] !!! Fatal Error: Steamcmd needs 250MB of free disk space to update.
+valheim-updater src/tier0/threadtools.cpp (3553) : Assertion Failed: Illegal termination of worker thread 'Thread(0x0x58a1d8f0/0x0xf7780b'
+```
+
+The only workaround they found was to use a non-ZFS volume for the container.
+
+If you have access to a QNAP NAS running ZFS and can reproduce/debug this issue further, please open a new issue with your findings so we can update this section and provide more information here.
+
+
 # License
 Copyright 2021 [Lukas Lösche](mailto:lukas@opensourcery.de)