docs: document changes to x and X

book/src/keymap.md

@@ -133,8 +133,8 @@ Normal mode is the default mode when you launch helix. You can return to it from
 | `Alt-(`               | Rotate selection contents backward                                | `rotate_selection_contents_backward` |
 | `Alt-)`               | Rotate selection contents forward                                 | `rotate_selection_contents_forward`  |
 | `%`                   | Select entire file                                                | `select_all`                         |
-| `x`                   | Select current line, if already selected, extend to next line     | `extend_line_below`                  |
+| `x`                   | Increase selection below by one line                              | `select_line_below`                  |
-| `X`                   | Extend selection to line bounds (line-wise selection)             | `extend_to_line_bounds`              |
+| `X`                   | Increase selection above by one line                              | `select_line_above`                  |
 | `Alt-x`               | Shrink selection to line bounds (line-wise selection)             | `shrink_to_line_bounds`              |
 | `J`                   | Join lines inside selection                                       | `join_selections`                    |
 | `Alt-J`               | Join lines inside selection and select the inserted space         | `join_selections_space`              |