docs: networking: convert ip-sysctl.txt to ReST

- add SPDX header;
- adjust titles and chapters, adding proper markups;
- mark code blocks and literals as such;
- mark lists as such;
- mark tables as such;
- use footnote markup;
- adjust identation, whitespaces and blank lines;
- 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/admin-guide/kernel-parameters.txt

@@ -4910,7 +4910,7 @@
 			Set the number of tcp_metrics_hash slots.
 			Default value is 8192 or 16384 depending on total
 			ram pages. This is used to specify the TCP metrics
-			cache size. See Documentation/networking/ip-sysctl.txt
+			cache size. See Documentation/networking/ip-sysctl.rst
 			"tcp_no_metrics_save" section for more details.
 
 	tdfx=		[HW,DRM]

Documentation/admin-guide/sysctl/net.rst

@@ -353,7 +353,7 @@ socket's buffer. It will not take effect unless PF_UNIX flag is specified.
 
 3. /proc/sys/net/ipv4 - IPV4 settings
 -------------------------------------
-Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
+Please see: Documentation/networking/ip-sysctl.rst and ipvs-sysctl.txt for
 descriptions of these entries.
 
 

Documentation/networking/index.rst

@@ -69,6 +69,7 @@ Contents:
    ip_dynaddr
    iphase
    ipsec
+   ip-sysctl
 
 .. only::  subproject and html
 

Documentation/networking/snmp_counter.rst

@@ -792,7 +792,7 @@ counters to indicate the ACK is skipped in which scenario. The ACK
 would only be skipped if the received packet is either a SYN packet or
 it has no data.
 
-.. _sysctl document: https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt
+.. _sysctl document: https://www.kernel.org/doc/Documentation/networking/ip-sysctl.rst
 
 * TcpExtTCPACKSkippedSynRecv
 

net/Kconfig

@@ -86,7 +86,7 @@ config INET
 	  "Sysctl support" below, you can change various aspects of the
 	  behavior of the TCP/IP code by writing to the (virtual) files in
 	  /proc/sys/net/ipv4/*; the options are explained in the file
-	  <file:Documentation/networking/ip-sysctl.txt>.
+	  <file:Documentation/networking/ip-sysctl.rst>.
 
 	  Short answer: say Y.
 

net/ipv4/Kconfig

@@ -49,7 +49,7 @@ config IP_ADVANCED_ROUTER
 
 	  Note that some distributions enable it in startup scripts.
 	  For details about rp_filter strict and loose mode read
-	  <file:Documentation/networking/ip-sysctl.txt>.
+	  <file:Documentation/networking/ip-sysctl.rst>.
 
 	  If unsure, say N here.
 

net/ipv4/icmp.c

@@ -853,7 +853,7 @@ static bool icmp_unreach(struct sk_buff *skb)
 		case ICMP_FRAG_NEEDED:
 			/* for documentation of the ip_no_pmtu_disc
 			 * values please see
-			 * Documentation/networking/ip-sysctl.txt
+			 * Documentation/networking/ip-sysctl.rst
 			 */
 			switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
 			default: