Refer to historical macOS versions by their original name

guide/xml/installing.xml

@@ -114,7 +114,7 @@
         <section xml:id="installing.xcode.other">
             <title>Install Xcode on Older Releases of Mac OS X</title>
 
-            <para>If you have an earlier release of Mac OS X, you may download the latest version of Xcode for OS X 10.5
+            <para>If you have an earlier release of Mac OS X, you may download the latest version of Xcode for Mac OS X 10.5
                 (Xcode 3.0 and Xcode 3.1 Developer Tools) or 10.4 (Xcode 2.4.1 and Xcode 2.5 Developer Tools) from the
                 <link xlink:href="https://developer.apple.com/downloads/index.action">Apple developer website</link>.</para>
 

guide/xml/project.xml

@@ -422,7 +422,7 @@
           help when searching for tickets. It is not useful to list words here
           that already appear elsewhere in the ticket. Keywords also serve as
           tags; for example, use <quote>tiger</quote> if reporting a bug that
-          only affects OS X 10.4, <quote>haspatch</quote> if a fix is attached
+          only affects Mac OS X 10.4, <quote>haspatch</quote> if a fix is attached
           to the ticket, <quote>maintainer</quote> if you are the port's
           maintainer, or <quote>LP64</quote> if reporting an issue that only
           affects 64-bit platforms.</para>