Add a note on Spitfire plugins and Wine prefixes

I was pretty sure something like this was already in there, apparently
not.

README.md

@@ -520,6 +520,12 @@ include:
   and then use `udisksctl mount -t udf -o unhide -b /dev/loopX` where
   `/dev/loopX` corresponds to the loop device printed by the `loop-setup`
   command to mount the .iso file to a directory in `/run/media`.
+- If **Spitfire Audio** plugins like **BBC Symphony Orchestra** and **LABS** are
+  unable to load their sample libraries (_Error #X: Something went wrong_), then
+  you should try reinstalling those plugins to a new, clean Wine prefix. Make
+  sure to uninstall them along with their associated VST2 and VST3 plugins from
+  your main Wine prefix first before installing them to the new prefix to avoid
+  mixups.
 - **MeldaProduction** plugins have minor rendering issues when GPU acceleration
   is enabled. This can be fixed by disabling GPU acceleration in the plugin
   settings. I'm not sure whether this is an issue with Wine or the plugins