sflow: Write "sFlow" as "sFlow(R)" in documentation.

The sFlow license requires sFlow to be written as sFlow(R) for the first
reference in user documentation, so this commit implements that.

Suggested by Justin Pettit.

Author: blp

README

@@ -6,7 +6,7 @@ What is Open vSwitch?
 Open vSwitch is a multilayer software switch licensed under the open
 source Apache 2 license.  Our goal is to implement a production
 quality switch platform that supports standard management interfaces
-(e.g. NetFlow, sFlow, RSPAN, ERSPAN, IOS-like CLI), and opens the
+(e.g. NetFlow, sFlow(R), RSPAN, ERSPAN, IOS-like CLI), and opens the
 forwarding functions to programmatic extension and control.
 
 Open vSwitch is well suited to function as a virtual switch in VM

vswitchd/ovs-vswitchd.8.in

@@ -48,7 +48,7 @@ Port mirroring, with optional VLAN tagging.
 NetFlow v5 flow logging.
 .
 .IP \(bu
-sFlow monitoring.
+sFlow(R) monitoring.
 .
 .IP \(bu
 Connectivity to an external OpenFlow controller, such as NOX.

vswitchd/ovs-vswitchd.conf.5.in

@@ -460,7 +460,7 @@ netflow.mybr.host=nflow.example.com:9995
 .fi
 .RE
 .SS "sFlow Monitoring"
-sFlow is a protocol for monitoring switches.  A bridge may be
+sFlow(R) is a protocol for monitoring switches.  A bridge may be
 configured to send sFlow records to sFlow collectors by defining the
 key \fBsflow.\fIbridge\fB.host\fR for each collector in the form
 \fIip\fR[\fB:\fIport\fR].  Records from \fIbridge\fR will be sent to