Update brain.csl to ama.csl dependent (#5546)

Author: POBrien333

brain.csl

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<style xmlns="http://purl.org/net/xbiblio/csl" version="1.0" default-locale="en-US">
+  <info>
+    <title>Brain</title>
+    <id>http://www.zotero.org/styles/brain</id>
+    <link href="http://www.zotero.org/styles/brain" rel="self"/>
+    <link href="http://www.zotero.org/styles/american-medical-association" rel="independent-parent"/>
+    <link href="https://academic.oup.com/brain/pages/General_Instructions" rel="documentation"/>
+    <category citation-format="numeric"/>
+    <category field="medicine"/>
+    <issn>0006-8950</issn>
+    <eissn>1460-2156</eissn>
+    <updated>2021-07-08T21:58:08+00:00</updated>
+    <rights license="http://creativecommons.org/licenses/by-sa/3.0/">This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 License</rights>
+  </info>
+</style>

dependent/brain.csl

@@ -5,7 +5,6 @@
     <title-short>DM</title-short>
     <id>http://www.zotero.org/styles/discovery-medicine</id>
     <link href="http://www.zotero.org/styles/discovery-medicine" rel="self"/>
-    <link href="http://www.zotero.org/styles/brain" rel="template"/>
     <link href="http://www.discoverymedicine.com/about/information-for-authors-of-discovery-medicine/" rel="documentation"/>
     <author>
       <name>Patrick O'Brien, PhD</name>