admin-guide: pm: intel_epb: Add SPDX license tag and copyright notice

Add an SPDX license tag and a copyright notice to the intel_epb.rst
file under Documentation/admin-quide/pm.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>

Documentation/admin-guide/pm/intel_epb.rst

+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
 ======================================
 Intel Performance and Energy Bias Hint
 ======================================
 
+:Copyright: |copy| 2019 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
 .. kernel-doc:: arch/x86/kernel/cpu/intel_epb.c
    :doc: overview