Use no-break hyphen for sounds

src/epub/text/chapter-21.xhtml

@@ -15,7 +15,7 @@
 			<p>“Who says that A-Kor is dead?” demanded one of the chiefs.</p>
 			<p>“Where is he then?” asked I-Gos. “Have not others disappeared whom O-Tar thought too well beloved for men so near the throne as they?”</p>
 			<p>The chief shook his head. “And I thought that, or knew it, rather; I’d join U-Thor at The Gate of Enemies.”</p>
-			<p>“<i>S-s-st</i>,” cautioned one; “here comes the licker of feet,” and all eyes were turned upon the approaching E-Thas.</p>
+			<p>“<i>S‑s‑st</i>,” cautioned one; “here comes the licker of feet,” and all eyes were turned upon the approaching E-Thas.</p>
 			<p>“<span xml:lang="x-mars">Kaor</span>, friends!” he exclaimed as he stopped among them, but his friendly greeting elicited naught but a few surly nods. “Have you heard the news?” he continued, unabashed by treatment to which he was becoming accustomed.</p>
 			<p>“What⁠—has O-Tar seen an <span xml:lang="x-mars">ulsio</span> and fainted?” demanded I-Gos with broad sarcasm.</p>
 			<p>“Men have died for less than that, ancient one,” E-Thas reminded him.</p>