update notes on how to run test

test/gui/README.md

@@ -8,22 +8,25 @@ context. Basically, it just installs the xeyes application which will allow
 testers to confirm that the window is shown on screen and the user can
 interact with it.
 
-## Set Up
-Make sure the proof-of-concept image is available, building it if necessary.
+This proof-of-concept image is built and pushed to the GitHub container
+registry ghcr.io, but you can built it locally if you have `docker`
+or `podman` available.
 ```
 cd image
-docker build . -t xeyes
-cd ..
+docker build . -t denv-test-gui-image
+# OR
+podman build . -t denv-test-gui-image
 ```
-Test using the source code of denv, both with environment variable sharing
-enabled and disabled since X11 window sharing does utilize some sharing.
+
+## The Test
+Test using the source code of denv and with environment variable sharing disabled
+in order to make sure the necessary variables are being shared.
 ```
-../../denv init xeyes:latest test
+mkdir test
 cd test
-```
+../../denv init --clean-env ghcr.io/tomeichlersmith/denv-test-gui-image:latest
+# OR, if built locally
+../../denv init --clean-env denv-test-gui-image:latest
 
-```
-../../../denv xeyes
-../../../denv config env all off
 ../../../denv xeyes
 ```