doc: updated YAML version representation in readline.md

All other versions in YAML throughout the docs start with _v_. Fix two
cases in `readline.md` that did not.

PR-URL: #31924
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

doc/api/readline.md

@@ -351,7 +351,7 @@ async function processLineByLine() {
 
 ### rl.line
 <!-- YAML
-added: 0.1.98
+added: v0.1.98
 -->
 
 * {string|undefined}
@@ -386,7 +386,7 @@ process.stdin.on('keypress', (c, k) => {
 
 ### rl.cursor
 <!-- YAML
-added: 0.1.98
+added: v0.1.98
 -->
 
 * {number|undefined}