docs: networking: convert xfrm_proc.txt to ReST

- add SPDX header;
- adjust title markup;
- adjust identation, whitespaces and blank lines where needed;
- 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/index.rst

@@ -118,6 +118,7 @@ Contents:
    x25-iface
    x25
    xfrm_device
+   xfrm_proc
 
 .. only::  subproject and html
 

Documentation/networking/xfrm_proc.rst

@@ -1,5 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================================
 XFRM proc - /proc/net/xfrm_* files
 ==================================
+
 Masahide NAKAMURA <nakam@linux-ipv6.org>
 
 
@@ -14,42 +18,58 @@ as part of the linux private MIB.  These counters can be viewed in
 
 Inbound errors
 ~~~~~~~~~~~~~~
+
 XfrmInError:
 	All errors which is not matched others
+
 XfrmInBufferError:
 	No buffer is left
+
 XfrmInHdrError:
 	Header error
+
 XfrmInNoStates:
 	No state is found
 	i.e. Either inbound SPI, address, or IPsec protocol at SA is wrong
+
 XfrmInStateProtoError:
 	Transformation protocol specific error
 	e.g. SA key is wrong
+
 XfrmInStateModeError:
 	Transformation mode specific error
+
 XfrmInStateSeqError:
 	Sequence error
 	i.e. Sequence number is out of window
+
 XfrmInStateExpired:
 	State is expired
+
 XfrmInStateMismatch:
 	State has mismatch option
 	e.g. UDP encapsulation type is mismatch
+
 XfrmInStateInvalid:
 	State is invalid
+
 XfrmInTmplMismatch:
 	No matching template for states
 	e.g. Inbound SAs are correct but SP rule is wrong
+
 XfrmInNoPols:
 	No policy is found for states
 	e.g. Inbound SAs are correct but no SP is found
+
 XfrmInPolBlock:
 	Policy discards
+
 XfrmInPolError:
 	Policy error
+
 XfrmAcquireError:
 	State hasn't been fully acquired before use
+
 XfrmFwdHdrError:
 	Forward routing of a packet is not allowed
 
@@ -57,26 +77,37 @@ Outbound errors
 ~~~~~~~~~~~~~~~
 XfrmOutError:
 	All errors which is not matched others
+
 XfrmOutBundleGenError:
 	Bundle generation error
+
 XfrmOutBundleCheckError:
 	Bundle check error
+
 XfrmOutNoStates:
 	No state is found
+
 XfrmOutStateProtoError:
 	Transformation protocol specific error
+
 XfrmOutStateModeError:
 	Transformation mode specific error
+
 XfrmOutStateSeqError:
 	Sequence error
 	i.e. Sequence number overflow
+
 XfrmOutStateExpired:
 	State is expired
+
 XfrmOutPolBlock:
 	Policy discards
+
 XfrmOutPolDead:
 	Policy is dead
+
 XfrmOutPolError:
 	Policy error
+
 XfrmOutStateInvalid:
 	State is invalid, perhaps expired