Add even more documentation

knots/sort.scm

@@ -54,6 +54,15 @@
                 rest)))))
 
 (define* (fibers-sort! items less #:key parallelism)
+  "Sort ITEMS destructively using LESS as the comparison procedure,
+using a parallel merge sort.  Returns the sorted list.
+
+Splits ITEMS into chunks, sorts each in an eager fiber-promise in
+parallel, then merges pairs of sorted chunks in parallel until one
+sorted list remains.
+
+@code{#:parallelism} sets the number of initial chunks.  Defaults to
+the current fibers parallelism."
   (define requested-chunk-count
     (or parallelism
         (+ 1 (length (scheduler-remote-peers (current-scheduler))))))