add overriding .desktop files section

infrastructure/graduated/arch/README.md

@@ -44,6 +44,8 @@ instructions for building a:
   - [Software Stores](#software-stores)
     - [Flatpak](#flatpak)
     - [AppImage](#appimage)
+    - [Overriding .desktop files](#overriding-desktop-files)
+      - [Flatpak](#flatpak-1)
 
 ## Installation
 
@@ -820,3 +822,22 @@ Make sure to chmod +x the `.appimage` file before running.
 
 4. `desktop-file-validate ~/.local/share/applications/*.desktop`
 5. `update-desktop-database`
+
+### Overriding .desktop files
+
+Sometimes you need to make changes to the default .desktop files. You can do this by copying
+the .desktop file to `~/.local/share/applications/` and editing its settings.
+
+Finding the .desktop file can be tricky. I usually use the following find command:
+
+```bash
+# 2>/dev/null pipes all the "permission denied" errors to /dev/null
+# Searching in the btr_pools/root/root will skip .snapshots, /home, and /proc, /sys, etc.
+find /btr_pools/root/root/ -name '*.desktop' 2>/dev/null
+```
+
+#### Flatpak
+
+```bash
+cp /var/lib/flatpak/exports/share/applications/... ~/.local/share/applications/
+```