card: note the future direction (an adapter that assigns compute on its own)

README.md

@@ -22,7 +22,11 @@ clear rough edges listed below. We are publishing it as an intermediate
 release while we try something considerably more ambitious that may or may
 not work (an all-in-one adapter that internalises the whole two-pass
 pipeline). If that lands it will replace this file; if it does not, this
-one still does a useful job.
+one still does a useful job. Part of that work is finding out whether an
+adapter can be made to actually assign more compute to the burst on its
+own (a variable-rate attention behaviour learned inside the model, rather
+than the nodes stretching the clock for it); this pilot does not do that,
+see the mechanics note below.
 
 ## What it does