Remove double-Ls in some cases of signal(l)ing/signal(l)ed

lib/convert.js

@@ -248,6 +248,9 @@ function getBodyXML(chapter, contentEl) {
   xml = xml.replace(/([^a-zA-Z])ok([^a])/g, "$1okay$2");
   xml = xml.replace(/a-okay/g, "A-okay");
 
+  // Signal(l)ing/signal(l)ed are spelled both ways. Both are acceptable in English. Let's standardize on single-L.
+  xml = xml.replace(/(S|s)ignall/g, "$1ignal");
+
   // One-off fixes
   (substitutions[chapter.url] || []).forEach(substitution => {
     const indexOf = xml.indexOf(substitution.before);