Add SELinux section to test network docs #3788

Job	Run time
Basic Checks	3m 26s
Unit Tests	8m 47s
Integration Tests (raft)	13m 5s
Integration Tests (pvtdata)	12m 26s
Integration Tests (pvtdatapurge e2e)	12m 5s
Integration Tests (ledger)	12m 47s
Integration Tests (lifecycle)	6m 20s
Integration Tests (smartbft)	21m 25s
Integration Tests (discovery gossip devmode pluggable)	6m 26s
Integration Tests (gateway idemix pkcs11 configtx configtxlator)	18m 6s
Integration Tests (sbe nwo msp)	7m 53s
	2h 2m 46s

Provide feedback