Update README.md

discussing that it is impossible to use multiple versions of the same plugin and how to downgrade if you must.

Author: LinuxBeaver

README.md

@@ -138,4 +138,10 @@ ninja -C build
 
 ![image](https://github.com/LinuxBeaver/GEGL-Effects---Layer-Effects-in-Gimp-using-GEGL/assets/78667207/ddb15664-2e4a-4b3a-a5ff-e27d78899e74)
 
+### Downgrading to older versions of my plugins
+
+If you choose to downgrade GEGL Effects or any of my plugins that has a GEGL Enum List (blend mode switchers) to an earlier version, you must go to `/config/GIMP/2.10/filters` and delete the
+saved settings file associate with the plugin. You can find it by searching the plugins name,  If this is not done it will keep reporting that a file is corrupt and not allow you to make
+presets.** MULTIPLE VERSIONS OF ANY OF MY PLUGINS CANNOT CO-EXIST.** Gimp will always select the earliest one.  The only exception to this is a build of GEGL Effects I provided where I renamed the ENUM list to make them co-compatible. I recommend you don't downgrade unless you know what you are doing.
+