docs(user-event): Fix special character casing (#796)

Update to special character commands to correct camel case format.

Author: dalebaldwin

docs/ecosystem-user-event.mdx

@@ -462,15 +462,15 @@ method.
 
 | Key        | Character      |
 | ---------- | -------------- |
-| arrowLeft  | `{arrowleft}`  |
-| arrowRight | `{arrowright}` |
-| arrowDown  | `{arrowdown}`  |
-| arrowUp    | `{arrowup}`    |
+| arrowLeft  | `{arrowLeft}`  |
+| arrowRight | `{arrowRight}` |
+| arrowDown  | `{arrowDown}`  |
+| arrowUp    | `{arrowUp}`    |
 | enter      | `{enter}`      |
 | escape     | `{esc}`        |
 | delete     | `{del}`        |
 | backspace  | `{backspace}`  |
-| selectAll  | `{selectall}`  |
+| selectAll  | `{selectAll}`  |
 | space      | `{space}`      |
 | whitespace | `' '`          |