doc (Preprocessor): Extract into own file

* doc/Makefile.am (tame_TEXINFOS): Add `preproc.texi'.
* doc/preproc.texi: New file.
* doc/tame.texi: Extract `Preprocessing' section.

doc/Makefile.am

@@ -27,7 +27,7 @@ stylesheets := $(shell find "$(path_src)" \
 stexi       := $(stylesheets:.xsl=.texi)
 
 info_TEXINFOS = tame.texi
-tame_TEXINFOS = about.texi license.texi $(stexi) tame.css
+tame_TEXINFOS = about.texi preproc.texi license.texi $(stexi) tame.css
 
 MAKEINFOHTML=$(MAKEINFO) --html --css-include tame.css
 

doc/preproc.texi

@@ -0,0 +1,27 @@
+\input texinfo
+@c  This document is part of the TAME manual.
+@c  Copyright (C) 2015, 2016, 2018, 2019 R-T Specialty, LLC.
+@c    Permission is granted to copy, distribute and/or modify this document
+@c    under the terms of the GNU Free Documentation License, Version 1.3 or
+@c    any later version published by the Free Software Foundation; with no
+@c    Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+@c    A copy of the license is included in the section entitled ``GNU Free
+@c    Documentation License''.
+
+@node Preprocessor
+@appendix Preprocessor
+
+@menu
+* Macro Expansion::
+@end menu
+
+@node Macro Expansion
+@section Macro Expansion
+
+@menu
+* Expansion Sequence::
+@end menu
+
+@lowersections
+@include src/preproc/expand/expand-sequence.texi
+@raisesections

doc/tame.texi

@@ -98,25 +98,7 @@ TAME
 @end ifhtml
 
 @include about.texi
-
-
-@node Preprocessor
-@appendix Preprocessor
-
-@menu
-* Macro Expansion::
-@end menu
-
-@node Macro Expansion
-@section Macro Expansion
-
-@menu
-* Expansion Sequence::
-@end menu
-
-@lowersections
-@include src/preproc/expand/expand-sequence.texi
-@raisesections
+@include preproc.texi
 
 @include src/graph.texi
 @include src/symtable.texi