yama: clarify ptrace_scope=2 in Yama documentation

Current phrasing is ambiguous since it's unclear if attaching to a
children through PTRACE_TRACEME requires CAP_SYS_PTRACE. Rephrase the
sentence to make that clear.
Signed-off-by: Yves-Alexis Perez <corsac@corsac.net>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/LSM/Yama.rst

@@ -64,8 +64,8 @@ The sysctl settings (writable only with ``CAP_SYS_PTRACE``) are:
     Using ``PTRACE_TRACEME`` is unchanged.
 
 2 - admin-only attach:
-    only processes with ``CAP_SYS_PTRACE`` may use ptrace
-    with ``PTRACE_ATTACH``, or through children calling ``PTRACE_TRACEME``.
+    only processes with ``CAP_SYS_PTRACE`` may use ptrace, either with
+    ``PTRACE_ATTACH`` or through children calling ``PTRACE_TRACEME``.
 
 3 - no attach:
     no processes may use ptrace with ``PTRACE_ATTACH`` nor via