hints on "hg bisect";

--- a/README_REPOSITORY	Sun Aug 06 14:48:25 2023 +0200
+++ b/README_REPOSITORY	Sun Aug 06 16:01:11 2023 +0200
@@ -45,6 +45,21 @@
 
     isabelle/bin/isabelle doc system
 
+6. Find historical evidence about good or bad behaviour
+   (e.g. in Isabelle/jEdit):
+
+    cd isabelle
+    hg bisect --reset
+    Admin/init -R   #alternative: "hg up -r REV"
+
+    Admin/init && bin/isabelle jedit
+    hg bisect --good
+
+    Admin/init && bin/isabelle jedit
+    hg bisect --bad
+
+    ...
+
 
 Introduction
 ------------