docs: mention Termux extension workarounds

Author: jonaskuske

docs/termux.md

@@ -87,6 +87,31 @@ Potential Workaround :
 1. Create a soft-link from the debian-fs to your folder in `/sdcard`
 2. Use git from termux (preferred)
 
+### Many extensions including language packs fail to install
+
+Issue: Android is not seen as a Linux environment but as a separate, unsupported platform, so code-server only allows [Web Extensions](https://code.visualstudio.com/api/extension-guides/web-extensions), refusing to install extensions that run on the server.
+Fix: None\
+Potential workaround :
+
+You can manually download extensions as `.vsix` file and install them via `Extensions: Install from VSIX...` in the Command Palette.
+
+Alternatively, you can override `process.platform` to `linux`:
+
+Create a JS script that patches `process.platform`:
+
+```
+// android-as-linux.js
+Object.defineProperty(process, 'platform', { get() { return 'linux' }});
+```
+
+Then use Node's `--require` option to make sure it is loaded before `code-server` starts:
+
+```sh
+NODE_OPTIONS="--require /path/to/android-as-linux.js" code-server
+```
+
+⚠️ Note that Android and Linux are not 100% compatible, so use these workarounds at your own risk. Extensions that have native dependencies other than Node or interact with the OS directly might cause issues. 
+
 ## Extra
 
 ### Create a new user