Fix header;

Author: bjornbytes

guides/Compiling.md

@@ -16,7 +16,7 @@ LÖVR is currently known to work with (and optimized for)
 
 Other systems and hardware may work, but are not frequently tested.
 
-#### Physics SIMD
+### Physics SIMD
 
 When building for x86, the physics module requires a CPU with AVX/AVX2 support.  To work around
 this, disable the physics module by compiling with `-DLOVR_ENABLE_PHYSICS=OFF`, or compile with the