[wiki] added guide to fix missing in-game icons in linux

docs/wiki/Linux.md

@@ -47,6 +47,18 @@ Once Proton is installed, when you open your BSManager application for the first
 
 # Troubleshooting
 
+## Missing Icons in game
+
+<p align="center">
+    <img src="../assets/linux-missing-icons.png" alt="Linux Missing Icons" width="300"/>
+    <br>
+    NOTE: "?" are missing unicode icons
+</p>
+
+This is due to [BSML](https://github.com/monkeymanboy/BeatSaberMarkupLanguage) using a missing font (`Segoe UI Symbols`) for unicode emojis.
+
+To fix the issue, you need to get a copy of `seguisym.ttf` from the fonts folder an official copy Windows. Once you have a copy, add the font file to `~/.steam/steam/steamapps/compatdata/620980/pfx/drive_c/windows/Fonts`.
+
 ## Permission denied on "bs-versions.json"
 
 <pre>