prompt: update README to reflect additional usage with output dialog

README.md

@@ -59,7 +59,7 @@
 | [jsonl](/src/cmd/jsonl.rs#L2)<br>🚀🔣 | Convert newline-delimited JSON ([JSONL](https://jsonlines.org/)/[NDJSON](http://ndjson.org/)) to CSV. See `tojsonl` command to convert CSV to JSONL.
 | <a name="luau_deeplink"></a><br>[luau](/src/cmd/luau.rs#L2) 👑<br>✨📇🌐🔣 ![CKAN](docs/images/ckan.png) | Create multiple new computed columns, filter rows, compute aggregations and build complex data pipelines by executing a [Luau](https://luau-lang.org) [0.625](https://github.com/Roblox/luau/releases/tag/0.625) expression/script for every row of a CSV file ([sequential mode](https://github.com/jqnatividad/qsv/blob/bb72c4ef369d192d85d8b7cc6e972c1b7df77635/tests/test_luau.rs#L254-L298)), or using [random access](https://www.webopedia.com/definitions/random-access/) with an index ([random access mode](https://github.com/jqnatividad/qsv/blob/bb72c4ef369d192d85d8b7cc6e972c1b7df77635/tests/test_luau.rs#L367-L415)).<br>Can process a single Luau expression or [full-fledged data-wrangling scripts using lookup tables](https://github.com/dathere/qsv-lookup-tables#example) with discrete BEGIN, MAIN and END sections.<br> It is not just another qsv command, it is qsv's [Domain-specific Language](https://en.wikipedia.org/wiki/Domain-specific_language) (DSL) with [numerous qsv-specific helper functions](https://github.com/jqnatividad/qsv/blob/113eee17b97882dc368b2e65fec52b86df09f78b/src/cmd/luau.rs#L1356-L2290) to build production data pipelines. |
 | [partition](/src/cmd/partition.rs#L2) | Partition a CSV based on a column value. |
-| [prompt](/src/cmd/prompt.rs#L2) | Open a file dialog to pick a file as input. |
+| [prompt](/src/cmd/prompt.rs#L2) | Open a file dialog to pick a file. |
 | [pseudo](/src/cmd/pseudo.rs#L2)<br>🔣 | [Pseudonymise](https://en.wikipedia.org/wiki/Pseudonymization) the value of the given column by replacing them with an incremental identifier.  |
 | [py](/src/cmd/python.rs#L2)<br>✨🔣 | Create a new computed column or filter rows by evaluating a python expression on every row of a CSV file. Python's [f-strings](https://www.freecodecamp.org/news/python-f-strings-tutorial-how-to-use-f-strings-for-string-formatting/) is particularly useful for extended formatting, [with the ability to evaluate Python expressions as well](https://github.com/jqnatividad/qsv/blob/4cd00dca88addf0d287247fa27d40563b6d46985/src/cmd/python.rs#L23-L31). |
 | [rename](/src/cmd/rename.rs#L2) |  Rename the columns of a CSV efficiently. |