Add |br| for a line break.

Author: rdzman

prolog.rst.txt

@@ -15,6 +15,8 @@
     They should match the corresponding version in premable.tex.txt
     -------------------------------------------------------------------
 
+.. |br| replace:: :raw-html:`<br \>`:raw-latex:`\\`
+
 .. |MATPOWER| replace:: :raw-html:`M<span style="font-size:smaller">ATPOWER</span>`:raw-latex:`\matpower{}`
 .. |/MATPOWER/| replace:: :raw-html:`<em>M<span style="font-size:smaller">ATPOWER</span></em>`:raw-latex:`\matpoweri{}`
 .. |*MATPOWER*| replace:: :raw-html:`<strong>M<span style="font-size:smaller">ATPOWER</span></strong>`:raw-latex:`\matpowerb{}`