[docs] Update HTML pages to refer to CSS in a way that works locally and with Sphinx.

llvm-svn: 155153
diff --git a/llvm/docs/CodeGenerator.html b/llvm/docs/CodeGenerator.html
index c4b15df..2829a94 100644
--- a/llvm/docs/CodeGenerator.html
+++ b/llvm/docs/CodeGenerator.html
@@ -4,7 +4,7 @@
 <head>
   <meta http-equiv="content-type" content="text/html; charset=utf-8">
   <title>The LLVM Target-Independent Code Generator</title>
-  <link rel="stylesheet" href="llvm.css" type="text/css">
+  <link rel="stylesheet" href="_static/llvm.css" type="text/css">
 
   <style type="text/css">
     .unknown { background-color: #C0C0C0; text-align: center; }