user mode: show how to run /bin/sh on user mode

Author: cirosantilli

README.adoc

@@ -3643,6 +3643,26 @@ If you followed <<qemu-buildroot-setup>>, you can now run the executables create
 ;
 ....
 
+To easily explore the userland executable environment interactively, you can do:
+
+....
+./run \
+  --arch aarch64 \
+  --userland "$(./getvar --arch aarch64 buildroot_target_dir)/bin/sh" \
+  --terminal \
+;
+....
+
+or:
+
+....
+./run \
+  --arch aarch64 \
+  --userland "$(./getvar --arch aarch64 buildroot_target_dir)/bin/sh"  \
+  --userland-args='-c "uname -a && pwd"' \
+;
+....
+
 Here is an interesting examples of this: <<linux-test-project>>
 
 === User mode simulation with glibc