doc: Update documentation for Traffic Engineering

Signed-off-by: Olivier Dugeon <olivier.dugeon@orange.com>
diff --git a/doc/quagga.texi b/doc/quagga.texi
index 6508962..6831b30 100644
--- a/doc/quagga.texi
+++ b/doc/quagga.texi
@@ -85,6 +85,7 @@
 * RIPng::
 * OSPFv2::
 * OSPFv3::
+* ISIS::
 * BGP::
 * Configuring Quagga as a Route Server::
 * VTY shell::
@@ -109,6 +110,7 @@
 @include ripngd.texi
 @include ospfd.texi
 @include ospf6d.texi
+@include isisd.texi
 @include bgpd.texi
 @include routeserver.texi
 @include vtysh.texi