net{perf,server}: add page (#12075)

* netperf: add pages

* move pages to common; adjust syntax

* use placeholder syntax for port numbers

* Add mnemonics and manned.org link per style guide

* missing period

* Add commas

pages/common/netperf.md

@@ -0,0 +1,21 @@
+# netperf
+
+> Client-side command for `netperf`, the benchmarking application that measures network throughput. Similar to `iperf`.
+> See also: `netserver`, for the server-side command.
+> More information: <https://hewlettpackard.github.io/netperf/doc/netperf.html#Global-Command_002dline-Options>.
+
+- Connect to server on a specific IP address via default port (12865):
+
+`netperf {{address}}`
+
+- Specify [p]ort:
+
+`netperf {{address}} -p {{port}}`
+
+- Specify the sampling [l]ength in seconds (default is 10):
+
+`netperf {{address}} -l {{seconds}}`
+
+- Force IPv[4] or IPv[6]:
+
+`netperf {{address}} -{{4|6}}`