doc: sort-group: unnecessary copy

* txr.1: Remove copy operation partition-by expression; this
was needed when sort was destructive.

1 files changed, 1 insertions, 1 deletions

diff --git a/txr.1 b/txr.1
index 90df466a..e6a2b381 100644
--- a/txr.1
+++ b/txr.1
@@ -36917,7 +36917,7 @@ The following equivalence holds:
 
   <-->
 
-  (partition-by kf (sort (copy sq) kf lf))
+  (partition-by kf (sort sq kf lf))
 .brev
 
 Note the reversed order of