docs: add SPDX tags to new index files

All those new files I added are under GPL v2.0 license.

Add the corresponding SPDX headers to them.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/admin-guide/blockdev/drbd/figures.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 .. The here included files are intended to help understand the implementation
 
 Data flows that Relate some functions, and write packets

Documentation/admin-guide/blockdev/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ===========================
 The Linux RapidIO Subsystem
 ===========================

Documentation/admin-guide/laptops/index.rst

+.. SPDX-License-Identifier: GPL-2.0
 
 ==============
 Laptop Drivers

Documentation/admin-guide/namespaces/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ==========
 Namespaces
 ==========

Documentation/admin-guide/perf/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ===========================
 Performance monitor support
 ===========================

Documentation/arm/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ================
 ARM Architecture
 ================

Documentation/arm/nwfpe/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ===================================
 NetWinder's floating point emulator
 ===================================

Documentation/arm/omap/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 =======
 TI OMAP
 =======

Documentation/arm/sa1100/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ====================
 Intel StrongARM 1100
 ====================

Documentation/arm/samsung-s3c24xx/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ==========================
 Samsung S3C24XX SoC Family
 ==========================

Documentation/arm/samsung/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ===========
 Samsung SoC
 ===========

Documentation/driver-api/early-userspace/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ===============
 Early Userspace
 ===============

Documentation/driver-api/md/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ====
 RAID
 ====

Documentation/driver-api/memory-devices/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 =========================
 Memory Controller drivers
 =========================

Documentation/driver-api/mmc/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ========================
 MMC/SD/SDIO card support
 ========================

Documentation/driver-api/mtd/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ==============================
 Memory Technology Device (MTD)
 ==============================

Documentation/driver-api/nfc/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ========================
 Near Field Communication
 ========================

Documentation/driver-api/nvdimm/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ===================================
 Non-Volatile Memory Device (NVDIMM)
 ===================================

Documentation/driver-api/phy/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 =====================
 Generic PHY Framework
 =====================

Documentation/driver-api/rapidio/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ===========================
 The Linux RapidIO Subsystem
 ===========================

Documentation/ia64/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 ==================
 IA-64 Architecture
 ==================