Document XTS txbridge timeout behaviour for bridged JTA transactions

With the Narayana release 5.9.4.Final there is changed the behaviour of timeout definition for bridged JTA transaction from XTS. The behaviour should be documented in the product documentation. The upstream documentation is here:
https://github.com/jbosstm/documentation/pull/49/files#diff-78df7546fde1355d1367bda6f6a90d34R95

The point is that

• if XTS context brings timeout then bridged JTA transaction uses it.
• if XTS context brings no timeout then bridged JTA transaction uses default container timeout (default timeout defined in the JBoss EAP)