update flatpak instructions

Author: arch

.gitignore

@@ -14,3 +14,4 @@ funscript_actions.csv
 linuxdeploy*.AppImage
 build-dir
 .flatpak-builder
+repo

build_flatpak.sh

@@ -4,4 +4,4 @@ sudo sysctl kernel.unprivileged_userns_clone=1
 flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
 # flatpak install flathub org.freedesktop.Platform//21.08 org.freedesktop.Sdk//21.08
 flatpak install org.gnome.Platform//3.38 org.gnome.Sdk//3.38
-flatpak-builder build-dir org.flatpak.PythonFunscriptEditor.json --force-clean
+flatpak-builder --repo=repo --force-clean build-dir org.flatpak.PythonFunscriptEditor.json

contrib/flatpak/README.md

@@ -1,9 +1,26 @@
 # Flatpak
 
-## Cheatsheet
+## Build Flatpak from Source
+
+Run in project root:
 
 ```bash
 ./build_flatpak.sh
-flatpak-builder --run build-dir org.flatpak.PythonFunscriptEditor.json /bin/bash
-flatpak-builder --run build-dir org.flatpak.PythonFunscriptEditor.json runner.sh
+```
+
+To verify that the build was successful, run the following:
+
+```bash
+flatpak --user remote-add --no-gpg-verify local-repo repo
+flatpak --user install local-repo org.flatpak.PythonFunscriptEditor
+flatpak run org.flatpak.PythonFunscriptEditor
+flatpak --user remote-delete local-repo
+```
+
+An other option is to use `flatpak-builder` to install the application.
+
+```
+flatpak-builder --user --install --force-clean build-dir org.flatpak.PythonFunscriptEditor.json
+flatpak run org.flatpak.PythonFunscriptEditor
+flatpak uninstall org.flatpak.PythonFunscriptEditor
 ```