Added 2 movement shortcuts (#1903)

* Added 2 movement shortcuts

In the Document section, "Move down/up by n lines"

* Update vim.md

Co-authored-by: Rico Sta. Cruz <rstacruz@users.noreply.github.com>

vim.md

@@ -70,8 +70,10 @@ Getting started
 | ---         | ---                      |
 | `gg`        | First line               |
 | `G`         | Last line                |
-| `:n`     | Go to line `n` |
-| `nG`     | Go to line `n` |
+| `:{number}` | Go to line `{number}`    |
+| `{number}G` | Go to line `{number}`    |
+| `{number}j` | Go down `{number}` lines |
+| `{number}k` | Go up `{number}` lines   |
 {: .-shortcuts}
 
 #### Window