Update ios-press-books.csl (#5030)

Author: amararora13

ios-press-books.csl

@@ -82,6 +82,9 @@
     </layout>
   </citation>
   <bibliography and="text" second-field-align="flush" entry-spacing="0">
+    <sort>
+      <key variable="author"/>
+    </sort>
     <layout suffix=".">
       <text variable="citation-number" prefix="[" suffix="]"/>
       <text macro="author" suffix=", "/>