Add tmux scripts for ttcn3-{msc,bsc,bts}-test

Change-Id: I201b77c013cbeef9d1a07b9422b27f375811ed69
diff --git a/README b/README
index 7f1b594..f4f4eda 100644
--- a/README
+++ b/README
@@ -169,6 +169,15 @@
 
 [1] https://jenkins.osmocom.org/jenkins/view/TTCN3/
 
+=== ttcn3/tmux
+
+It's possible to run TTCN-3 test cases without using Docker.  This directory
+contains scripts for starting a testsuite and the related binaries in a tmux
+session.  For example, ttcn3-bsc-test.sh does the following:
+
+* Starts osmo-bsc, osmo-stp, and three instances of osmo-bts-omldummy.
+* Prepares a command for execuring the test suite.
+
 === Troubleshooting
 
 When using sanitize.opts, osmo-trx is not built with the address sanitizer