kimito_en: use Markdown bold for column titles

Swap the <b>…</b> title tags for **…** now that the columns shorthand
converts Markdown emphasis to wikitext. Rendered output is unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

kairo/kimito_en.md

@@ -14,7 +14,7 @@ The classic. Old working notes in [another page](Looking_into_You_and_me_\(ry_an
 
 ## Lyrics
 ```columns
-<b>君と私と穏やかな旅</b>
+**君と私と穏やかな旅**
 
 いつか見た夢の話
 遠い遠い国のこと
@@ -55,7 +55,7 @@ The classic. Old working notes in [another page](Looking_into_You_and_me_\(ry_an
 いつか思い出すよ
 この旅路を
 ===
-<b>You and me and a gentle journey</b>
+**You and me and a gentle journey**
 
 You know there was a dream I had long ago
 Of a somewhere that is far away