ICU-10853 mention trying an absolute path to runConfigureICU if the relative path doesn't work.

X-SVN-Rev: 36350

icu4c/readme.html

@@ -675,7 +675,12 @@
 ~/icu$ mkdir trunk-dev
 ~/icu$ cd trunk-dev
 ~/icu/trunk-dev$ ../trunk/source/runConfigureICU Linux
-~/icu/trunk-dev$ make check</pre></li>
+~/icu/trunk-dev$ make check</pre><br>
+        (Note: this example shows a relative path to
+         <code>runConfigureICU</code>. If you experience difficulty,
+         try using an absolute path to <code>runConfigureICU</code>
+         instead.)
+      </li>
     </ul>
     <h4>ICU as a System-Level Library</h4>
     <p>If ICU is installed as a system-level library, there are further