Use consistent spelling for “number plate”

src/epub/content.opf

@@ -36,7 +36,7 @@
 		<meta property="se:subject">Fiction</meta>
 		<dc:description id="description">A British wine merchant on business in France stumbles across a syndicate with something to hide, and resolves to discover their secret.</dc:description>
 		<meta id="long-description" property="se:long-description" refines="#description">
-			&lt;p&gt;&lt;i&gt;The Pit-Prop Syndicate&lt;/i&gt; is a story from the beginning of the golden age of crime fiction. Seymour Merriman, a British wine merchant on business in France, happens upon a syndicate manufacturing pit-props—beams used to prop up mine tunnels—but his eye is caught by one odd detail: their lorry’s numberplate mysteriously changes. With the help of his friend Hilliard from the Excise department they dig deeper and uncover a dangerous conspiracy.&lt;/p&gt;
+			&lt;p&gt;&lt;i&gt;The Pit-Prop Syndicate&lt;/i&gt; is a story from the beginning of the golden age of crime fiction. Seymour Merriman, a British wine merchant on business in France, happens upon a syndicate manufacturing pit-props—beams used to prop up mine tunnels—but his eye is caught by one odd detail: their lorry’s number plate mysteriously changes. With the help of his friend Hilliard from the Excise department they dig deeper and uncover a dangerous conspiracy.&lt;/p&gt;
 			&lt;p&gt;&lt;a href="https://standardebooks.org/ebooks/freeman-wills-crofts"&gt;Freeman Wills Crofts&lt;/a&gt; was a civil engineer, turned author of crime fiction. Though somewhat forgotten today, his style was widely appreciated at the time, and still finds fans of those who like a puzzle where all the loose ends are tied up. During his career he wrote over thirty crime novels; &lt;i&gt;The Pit-Prop Syndicate&lt;/i&gt;, published in 1922, was his third.&lt;/p&gt;
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 		<dc:language>en-GB</dc:language>