run.sh shortcut, m5 executable userland

build-m5

@@ -6,6 +6,14 @@ import common
 from shell_helpers import LF
 
 class Main(common.BuildCliFunction):
+    def __init__(self):
+        super().__init__(
+            description='''\
+Build the gem5 m5 executable.
+See: https://cirosantilli.com/linux-kernel-module-cheat#gem5-m5-executable
+'''
+        )
+
     def _get_make_cmd(self):
         allowed_toolchains = ['buildroot']
         if self.env['arch'] == 'x86_64':