Define "auxiliary action" and refer to that in description

The transient input change accidentally reused the previously
defined term "transient action" in a place that was intended
to refer to a non-primary action, and that was inconsistent
since transient actions include both primary actions and
device-specific auxiliary actions such as secondary pointers.

Author: klausw

index.bs

@@ -1613,7 +1613,7 @@ When an [=XR input source=] |source| for {{XRSession}} |session| has its [=prima
 Transient input {#transient-input}
 ---------------
 
-Some [=/XR device=]s may support <dfn>transient input sources</dfn>, where the [=XR input source=] is only meaningful while performing a <dfn>transient action</dfn>, either the [=primary action=] for a [=primary input source=], or a device-specific action for an [=auxiliary input source=]. An example would be mouse, touch, or stylus input against an {{XRSessionMode/"inline"}} {{XRSession}}, which MUST produce a transient {{XRInputSource}} with a {{targetRayMode}} set to {{screen}}, treated as a [=primary action=] for the [[POINTEREVENTS#dfn-primary-pointer]], and as a non-primary [=transient action=] for a non-primary pointer. [=Transient input sources=] are only present in the session's [=list of active XR input sources=] for the duration of the [=transient action=].
+Some [=/XR device=]s may support <dfn>transient input sources</dfn>, where the [=XR input source=] is only meaningful while performing a <dfn>transient action</dfn>, either the [=primary action=] for a [=primary input source=], or a device-specific <dfn>auxiliary action</dfn> for an [=auxiliary input source=]. An example would be mouse, touch, or stylus input against an {{XRSessionMode/"inline"}} {{XRSession}}, which MUST produce a transient {{XRInputSource}} with a {{targetRayMode}} set to {{screen}}, treated as a [=primary action=] for the [[POINTEREVENTS#dfn-primary-pointer]], and as a non-primary [=auxiliary action=] for a non-primary pointer. [=Transient input sources=] are only present in the session's [=list of active XR input sources=] for the duration of the [=transient action=].
 
 [=Transient input sources=] follow the following sequence when handling [=transient actions=] instead of the algorithms for non-transient [=primary actions=]: