OsmoGSMTester: Remove resolved TODO

Change-Id: Ie0f18293e566a690d2434d08cbaaf2fdf71d88e4
diff --git a/doc/manuals/chapters/config.adoc b/doc/manuals/chapters/config.adoc
index 335a603..8176b45 100644
--- a/doc/manuals/chapters/config.adoc
+++ b/doc/manuals/chapters/config.adoc
@@ -205,8 +205,6 @@
 - voice:trx+dyn_ts
 ----
 
-*TODO*: voice is not actually implemented yet
-
 === 'defaults.conf' (optional)
 
 Each binary run by osmo-gsm-tester, e.g. 'osmo-nitb' or 'osmo-bts-sysmo',