add a consistent set of text about X11

2006/grothe/README.md

@@ -4,6 +4,10 @@
     make
 ```
 
+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)".
+
 
 ## To use:
 

2006/grothe/index.html

@@ -409,6 +409,9 @@ Location: <a href="../../location.html#US">US</a> - <em>United States of America
 <!-- BEFORE: 1st line of markdown file: 2006/grothe/README.md -->
 <h2 id="to-build">To build:</h2>
 <pre><code>    make</code></pre>
+<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>
 <h2 id="to-use">To use:</h2>
 <pre><code>    ./grothe carrier_freq pixelclock horizontal_total &lt; some_input.txt</code></pre>
 <h2 id="try">Try:</h2>

2006/toledo3/README.md

@@ -4,6 +4,10 @@
     make
 ```
 
+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)".
+
 The author provided two alternate versions, one which adds a status bar and
 another that makes it text only. The author also provided a version that they
 tested with Windows.  See [alternate code](#alternate-code) below.

2006/toledo3/index.html

@@ -409,6 +409,9 @@ Location: <a href="../../location.html#MX">MX</a> - <em>United Mexican States</e
 <!-- BEFORE: 1st line of markdown file: 2006/toledo3/README.md -->
 <h2 id="to-build">To build:</h2>
 <pre><code>    make</code></pre>
+<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>
 <p>The author provided two alternate versions, one which adds a status bar and
 another that makes it text only. The author also provided a version that they
 tested with Windows. See <a href="#alternate-code">alternate code</a> below.</p>