Add troubleshooting note about host-mapped volume issue with MariaDB

[arobert3434]

Added note to README troubleshooting section about MariaDB startup with host-mapped data volume on Windows or Mac. (Try to save some investigation time for those hitting it.)

[j1cs]

Perfect. Also I would like if you can specify the workaround that works for you? You can put the link of the previous thread or wrote by you.
Thanks.

[arobert3434]

In my case I used a named but not mapped volume ( ... -v MY_NAME:/var/lib/mysql ...). I added a bit of clarification to the doc, but then realized the issue and fix are reported against MariaDB's own container, which is not used here. It might be you can add the argument --innodb-flush-method=fsync in your MySQL startup and/or try some of the other suggestions in the issue thread and it will fix it. But that might hurt performance on Linux hosts.

[j1cs]

Perfect. Merged!