Bugfix: only replace the first instance when inserting the estimated reading time

modules/feature-readingtime.php

@@ -23,11 +23,12 @@ register_module([
 				$insert = "<small><em>{$reading_time[0]} minute read</em></small>";
 			
 			// TODO: Create a canonical way to insert something just below the header - this might be tough though 'cause the that isn't handled by the page_renderer though
-			$replace_count = 1; // Without a temp variable we get "only variables can be passed by reference", ref PHP 7.4.6
-			$parts["{content}"] = str_replace(
-				"</h1>", "</h1><p class='system-text-insert readingtime-estimate'>$insert</p>",
+			$insert = "\n\t\t\t<p class='system-text-insert readingtime-estimate'>$insert</p>";
+			$parts["{content}"] = substr_replace(
 				$parts["{content}"],
-				$replace_count
+				"</h1>$insert",
+				strpos($parts["{content}"], "</h1>"),
+				5
 			);
 		});
 	}