add experimental to README
`gt` is a command line tool that performs convenient actions on a
gnucash sqlite3 database.
-**warning: gt can destroy your gnucash sqlite3 database**
+**warning: gt is experimental and can destroy your gnucash sqlite3 database**
`gt` is not associated with the gnucash project in anyway. There is no
guarantee that any action performed by `gt` will not corrupt, destroy or
--description "auto registration" \
--parent-account "expenses:automotive"
```
+
+Generate a profit and loss report:
+```shell
+$ gt report pl \
+ --start-date 2026-01-01 \
+ --end-date 2026-01-31
+```