docs: networking: convert netdev-features.txt to ReST

Not much to be done here:

- add SPDX header;
- adjust titles and chapters, adding proper markups;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/checksum-offloads.rst

@@ -59,7 +59,7 @@ recomputed for each resulting segment.  See the skbuff.h comment (section 'E')
 for more details.
 
 A driver declares its offload capabilities in netdev->hw_features; see
-Documentation/networking/netdev-features.txt for more.  Note that a device
+Documentation/networking/netdev-features.rst for more.  Note that a device
 which only advertises NETIF_F_IP[V6]_CSUM must still obey the csum_start and
 csum_offset given in the SKB; if it tries to deduce these itself in hardware
 (as some NICs do) the driver should check that the values in the SKB match

Documentation/networking/index.rst

@@ -81,6 +81,7 @@ Contents:
    mpls-sysctl
    multiqueue
    netconsole
+   netdev-features
 
 .. only::  subproject and html
 

Documentation/networking/netdev-features.rst

@@ -1,3 +1,6 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================================================
 Netdev features mess and how to get out from it alive
 =====================================================
 
@@ -6,8 +9,8 @@ Author:
 
 
 
- Part I: Feature sets
-======================
+Part I: Feature sets
+====================
 
 Long gone are the days when a network card would just take and give packets
 verbatim.  Today's devices add multiple features and bugs (read: offloads)
@@ -39,8 +42,8 @@ one used internally by network core:
 
 
 
- Part II: Controlling enabled features
-=======================================
+Part II: Controlling enabled features
+=====================================
 
 When current feature set (netdev->features) is to be changed, new set
 is calculated and filtered by calling ndo_fix_features callback
@@ -65,8 +68,8 @@ driver except by means of ndo_fix_features callback.
 
 
 
- Part III: Implementation hints
-================================
+Part III: Implementation hints
+==============================
 
  * ndo_fix_features:
 
@@ -94,8 +97,8 @@ Errors returned are not (and cannot be) propagated anywhere except dmesg.
 
 
 
- Part IV: Features
-===================
+Part IV: Features
+=================
 
 For current list of features, see include/linux/netdev_features.h.
 This section describes semantics of some of them.

include/linux/netdev_features.h

@@ -89,7 +89,7 @@ enum {
 	 * Add your fresh new feature above and remember to update
 	 * netdev_features_strings[] in net/core/ethtool.c and maybe
 	 * some feature mask #defines below. Please also describe it
-	 * in Documentation/networking/netdev-features.txt.
+	 * in Documentation/networking/netdev-features.rst.
 	 */
 
 	/**/NETDEV_FEATURE_COUNT