[education/kstars/stable-3.5.6] doc: USB entity causing build problems on Ubuntu 18.04 so reverting to regular text until 22.04 is released and 20.04 is the new baseline

[Jasem Mutlaq]

Git commit 05ce1040ebb577429b2a95a7bd45baea62d61d78 by Jasem Mutlaq.
Committed on 16/11/2021 at 22:50.
Pushed by mutlaqja into branch 'stable-3.5.6'.

USB entity causing build problems on Ubuntu 18.04 so reverting to regular text until 22.04 is released and 20.04 is the new baseline

M  +5    -5    doc/indi.docbook

https://invent.kde.org/education/kstars/commit/05ce1040ebb577429b2a95a7bd45baea62d61d78

diff --git a/doc/indi.docbook b/doc/indi.docbook
index f65631399..f690c2a71 100644
--- a/doc/indi.docbook
+++ b/doc/indi.docbook
@@ -84,14 +84,14 @@ run under one INDI server, and hence one port. Select multiple drivers then pres
 
 <para>Most telescopes are equipped with <hardware>RS232</hardware> interface
 for remote control. Connect the RS232 jack in your telescope to your
-computer's <hardware>Serial/&USB;</hardware> port. Traditionally, the RS232
+computer's <hardware>Serial/USB</hardware> port. Traditionally, the RS232
 connects to the serial port of your computer, but since many new laptops
-abandoned the serial port in favor of <hardware>&USB;/FireWire</hardware>
-ports, you might need to obtain a Serial to &USB; adaptor to use with new
+abandoned the serial port in favor of <hardware>USB/FireWire</hardware>
+ports, you might need to obtain a Serial to USB adaptor to use with new
 laptops.
 </para>
 
-<para>After connecting your telescope to the Serial/&USB; port, turn your
+<para>After connecting your telescope to the Serial/USB port, turn your
 telescope on. It is <emphasis>highly</emphasis> recommended that you
 download and install the latest firmware for your telescope
 controller.
@@ -706,7 +706,7 @@ the sky map. This procedure is described in detail in the
 <question>
 <para>
 When I try to <guibutton>Connect</guibutton>, &kstars; reports that the
-telescope is not connected to the serial/&USB; port. What can I do?
+telescope is not connected to the serial/USB port. What can I do?
 </para>
 </question>
 <answer>