Add SGML Makefile rule for single-page text, postgres.txt.

doc/src/sgml/Makefile

@@ -2,7 +2,7 @@
 #
 # PostgreSQL documentation makefile
 #
-# $PostgreSQL: pgsql/doc/src/sgml/Makefile,v 1.145 2010/06/12 15:42:44 momjian Exp $
+# $PostgreSQL: pgsql/doc/src/sgml/Makefile,v 1.146 2010/06/12 15:58:38 momjian Exp $
 #
 #----------------------------------------------------------------------------
 
@@ -108,6 +108,10 @@ html-stamp: postgres.sgml $(ALLSGML) stylesheet.dsl
 postgres.html: postgres.sgml $(ALLSGML) stylesheet.dsl
 	$(JADE.html.call) -V nochunks -V rootchunk -V '(define %root-filename% #f)' -V '(define use-output-dir #f)' -i include-index $<
 
+# single-page text
+postgres.txt: postgres.html
+	$(LYNX) -force_html -dump -nolist -stdin $< > $@
+
 HTML.index: postgres.sgml $(ALMOSTALLSGML) stylesheet.dsl
 	@$(MKDIR_P) html
 	$(JADE.html.call) -V html-index $<