more doc updates.

git-svn-id: http://root.cern.ch/svn/root/trunk@21493 27541ba8-7e3a-0410-8455-c3a389f83636

base/doc/index.txt

 BEGIN_HTML
-<p><hr><p>
+<p>
 The base classes of the ROOT system provide the core of the system. They
 are available to all other classes. They range from a set of abstract
 interfaces (TVirtualXXXXX classes), to a wide range of basic utility

chirp/doc/index.txt

+BEGIN_HTML
+This directory contains the I/O interface classes for the <b>Chrip</b> system.
+For more information about <b>Chrip</b>, see:
+<ul>
+<li><a href="http://www.cs.wisc.edu/condor/chirp">the Condor Chirp site</a></li>
+</ul>
+END_HTML

sql/doc/index.txt

-This directory contains all classes, related to the ROOT SQL file implementation.
 BEGIN_HTML
- See:
+This directory contains all classes, related to the ROOT SQL file
+implementation. See:
 <ul>
-<li> Main functionality of ROOT SQL documented in TSQLFile class </li>
-<li> See the chapter on <a href="ftp://root.cern.ch/root/doc/11InputOutput.pdf">Input/Output</a> for more on how TFile is to be used</li>
+<li>Main functionality of ROOT SQL documented in TSQLFile class </li>
+<li>See the chapter on <a href="ftp://root.cern.ch/root/doc/11InputOutput.pdf">Input/Output</a> for more on how TFile is to be used</li>
 </ul>
 END_HTML

xml/doc/index.txt

-This directory contains all classes, related to the ROOT xml file implementation.
 BEGIN_HTML
- See:
+This directory contains all classes, related to the ROOT XML file
+implementation. See:
 <ul>
-<li> Main functionality of ROOT xml documented in TXMLFile class </li>
-<li> Special xml parser for ROOT xml files implemented in TXMLEngine class </li>
-<li><a href="ftp://root.cern.ch/root/doc/11InputOutput.pdf">Some documentation can be found in the end of the Input/Output chapter
-    </a></li>
+<li>Main functionality of ROOT xml documented in TXMLFile class </li>
+<li>Special xml parser for ROOT xml files implemented in TXMLEngine class </li>
+<li><a href="ftp://root.cern.ch/root/doc/11InputOutput.pdf">Some documentation can be found in the end of the Input/Output chapter</a></li>
 </ul>
 END_HTML

xmlparser/doc/index.txt

+BEGIN_HTML
+This directory contains classes that provide and interface to the libxml2
+XML parser. Both DOM and SAX parser interfaces are provided.
+See:
+<ul>
+<li><a href="http://www.xmlsoft.org">For more on libxml2</a></li>
+</ul>
+END_HTML