[ASM] Add DOI for preprints. (#5862)

https://forums.zotero.org/discussion/94032/biorxiv-and-medrxiv-not-importing-properply-since-plugin-update#latest

american-society-for-microbiology.csl

@@ -5,7 +5,7 @@
     <title-short>ASM</title-short>
     <id>http://www.zotero.org/styles/american-society-for-microbiology</id>
     <link href="http://www.zotero.org/styles/american-society-for-microbiology" rel="self"/>
-    <link href="http://aem.asm.org/misc/journal-ita_org.dtl#03" rel="documentation"/>
+    <link href="https://journals.asm.org/references" rel="documentation"/>
     <author>
       <name>Julian Onions</name>
       <email>[email protected]</email>
@@ -126,6 +126,9 @@
           </else>
         </choose>
       </if>
+      <else-if type="article">
+        <text variable="DOI" prefix=" https://doi.org/"/>
+      </else-if>
       <else-if type="book webpage post post-weblog" match="any">
         <group delimiter=". " prefix=". ">
           <text variable="URL"/>