readme: reverse now has index support and can work in streaming mode

README.md

@@ -62,7 +62,7 @@
 | [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. |
 | [replace](/src/cmd/replace.rs#L2) | Replace CSV data using a regex. Applies the regex to each field individually. |
-| [reverse](/src/cmd/reverse.rs#L2)<br>🤯 | Reverse order of rows in a CSV. Unlike the `sort --reverse` command, it preserves the order of rows with the same key.  |
+| [reverse](/src/cmd/reverse.rs#L2)<br>📇🤯 | Reverse order of rows in a CSV. Unlike the `sort --reverse` command, it preserves the order of rows with the same key. If an index is present, it works with constant memory. Otherwise, it will load all the data into memory. |
 | <a name="safenames_deeplink"></a>[safenames](/src/cmd/safenames.rs#L2)<br>![CKAN](docs/images/ckan.png) | Modify headers of a CSV to only have ["safe" names](/src/cmd/safenames.rs#L5-L14) - guaranteed "database-ready"/"CKAN-ready" names.  |
 | [sample](/src/cmd/sample.rs#L2)<br>📇🌐🏎️ | Randomly draw rows (with optional seed) from a CSV using [reservoir sampling](https://en.wikipedia.org/wiki/Reservoir_sampling), using memory proportional to the sample size. If an index is present, using random indexing with constant memory. |
 | [schema](/src/cmd/schema.rs#L2)<br>📇😣🏎️ | Infer schema from CSV data, replete with data type & domain/range validation & output in [JSON Schema](https://json-schema.org/) format. Uses multithreading to go faster if an index is present. See `validate` command to use the generated JSON Schema to validate if similar CSVs comply with the schema. |