stack: Upgrade-Pfad bekommt eine eigene manual-Instruktion, INSTALL.md verweist darauf (#108)

Files changed:
- CHANGES.md
- INSTALL.md
- VERSION
- instructions/session-setup.md
- instructions/upgrade-instance.md
- tools/CONTRACT.md
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/tests/test_dist_upgrade.py

tools/chemenu/commands/dist_cmd.py

@@ -1045,8 +1045,13 @@ def run_upgrade(
         summary += (
             f" {len(migration_chain)} migration(s) now outstanding - run `wikitool migrate status`."
         )
+    # One pointer rather than a second copy of the order: the steps after the
+    # swap live in instructions/upgrade-instance.md, which ships with every
+    # instance. Naming the resume *command* rather than a step number keeps this
+    # line correct when that file's numbering moves.
     summary += (
-        " Nothing was committed. Now run, in order: `wikitool instructions sync`, `doctor`, "
-        "`docs verify`, `instructions verify`, `lint` - then restart the agent session."
+        " Nothing was committed and nothing is verified yet."
+        " `instructions/upgrade-instance.md` carries the order for everything that follows"
+        " and resumes at `wikitool instructions sync`."
     )
     success(summary)