add a consistent set of text about X11

1996/jonth/README.md

@@ -4,10 +4,9 @@
     make all
 ```
 
-NOTE: this entry requires `X11/Xlib.h` header file and the X11 library to
-compile. macOS users running Mountain Lion and later will need to download and
-install [XQuartz](https://www.xquartz.org) in order to compile and run this
-entry.
+NOTE: this entry requires the `X11/Xlib.h` header file and the X11 library to
+compile.  For more information see the
+FAQ on "[X11](../../faq.html#X11)".
 
 
 ### Bugs and (Mis)features:

1996/jonth/index.html

@@ -409,10 +409,9 @@ Location: <a href="../../location.html#NO">NO</a> - <em>Kingdom of Norway</em> (
 <!-- BEFORE: 1st line of markdown file: 1996/jonth/README.md -->
 <h2 id="to-build">To build:</h2>
 <pre><code>    make all</code></pre>
-<p>NOTE: this entry requires <code>X11/Xlib.h</code> header file and the X11 library to
-compile. macOS users running Mountain Lion and later will need to download and
-install <a href="https://www.xquartz.org">XQuartz</a> in order to compile and run this
-entry.</p>
+<p>NOTE: this entry requires the <code>X11/Xlib.h</code> header file and the X11 library to
+compile. For more information see the
+FAQ on “<a href="../../faq.html#X11">X11</a>”.</p>
 <h3 id="bugs-and-misfeatures">Bugs and (Mis)features:</h3>
 <p>The current status of this entry is:</p>
 <blockquote>