Add warning message to `session save` when transcript isn't saved. (#109020)

Somewhat recently, we made the change to hide the behavior to save LLDB
session history to the transcript buffer behind the flag
`interpreter.save-transcript`. By default, `interpreter.save-transcript`
is false. See #90703 for context.

I'm making a small update here to our `session save` messaging and some
help docs to clarify for users that aren't aware of this change. Maybe
`interpreter.save-transcript` could be true by default as well. Any
feedback welcome.

# Tests
```
bin/lldb-dotest -p TestSessionSave
```

---------

Co-authored-by: Tom Yang <toyang@fb.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/lldb/source/Commands/CommandObjectSession.cpp b/lldb/source/Commands/CommandObjectSession.cpp
index c381ba4..ac7eec5 100644
--- a/lldb/source/Commands/CommandObjectSession.cpp
+++ b/lldb/source/Commands/CommandObjectSession.cpp
@@ -19,7 +19,9 @@ public:
       : CommandObjectParsed(interpreter, "session save",
                             "Save the current session transcripts to a file.\n"
                             "If no file if specified, transcripts will be "
-                            "saved to a temporary file.",
+                            "saved to a temporary file.\n"
+                            "Note: transcripts will only be saved if "
+                            "interpreter.save-transcript is true.\n",
                             "session save [file]") {
     AddSimpleArgumentList(eArgTypePath, eArgRepeatOptional);
   }