add musl-cross info

documentation/modules/exploit/linux/local/ufo_privilege_escalation.md

@@ -35,6 +35,18 @@ To verify SMAP has been disabled, `grep smap /proc/cpuinfo` and nothing should b
   
   If we should live compile on the system, or drop pre-created binaries.  Auto will determine if gcc/libs are installed to compile live on the system.  Defaults to Auto
 
+## Compiled Executables
+
+The module makes use of a pre-compiled exploit executable to be
+used when `gcc` is not available on the target host for live compiling,
+or `COMPILE` is set to `False`.
+
+The executable was cross-compiled with [musl-cross](https://s3.amazonaws.com/muslcross/musl-cross-linux-6.tar).
+
+```bash
+./x86_64-linux-musl-gcc -o exploit.out -pie -static exploit.c
+```
+
 ## Scenarios
 
 ### Ubuntu 14.04.5 4.4.0-31-generic x64 Desktop