doc: convert manual from Texinfo to AsciiDoc

Split and convert the manual into four AsciiDoc documents, a document
about installation and three documents in the manpage type for
chrony.conf, chronyd and chronyc. The minimal man pages that were
maintained separately from the manual are replaced by full man pages
generated from AsciiDoc. Info files will no longer be provided.

Some parts of the manual are rewritten, updated or trimmed. The
introduction chapter is partially merged with README. The chapter about
typical operating scenarios is included in the chrony.conf man page.

doc/Makefile.in

@@ -0,0 +1,70 @@
+ADOC = asciidoctor
+ADOC_FLAGS =
+SED = sed
+HTML_TO_TXT = w3m -dump -T text/html
+
+MAN_FILES = chrony.conf.man chronyc.man chronyd.man
+TXT_FILES = faq.txt installation.txt
+HTML_FILES = $(MAN_FILES:%.man=%.html) $(TXT_FILES:%.txt=%.html)
+MAN_IN_FILES = $(MAN_FILES:%.man=%.man.in)
+
+SYSCONFDIR = @SYSCONFDIR@
+BINDIR = @BINDIR@
+SBINDIR = @SBINDIR@
+MANDIR = @MANDIR@
+DOCDIR = @DOCDIR@
+CHRONYSOCKDIR = @CHRONYSOCKDIR@
+CHRONYVARDIR = @CHRONYVARDIR@
+CHRONY_VERSION = @CHRONY_VERSION@
+DEFAULT_USER = @DEFAULT_USER@
+DEFAULT_HWCLOCK_FILE = @DEFAULT_HWCLOCK_FILE@
+
+SED_COMMANDS = "s%\@SYSCONFDIR\@%$(SYSCONFDIR)%g;\
+	       s%\@BINDIR\@%$(BINDIR)%g;\
+	       s%\@SBINDIR\@%$(SBINDIR)%g;\
+	       s%\@CHRONY_VERSION\@%$(CHRONY_VERSION)%g;\
+	       s%\@DEFAULT_HWCLOCK_FILE\@%$(DEFAULT_HWCLOCK_FILE)%g;\
+	       s%\@DEFAULT_USER\@%$(DEFAULT_USER)%g;\
+	       s%\@CHRONYSOCKDIR\@%$(CHRONYSOCKDIR)%g;\
+	       s%\@CHRONYVARDIR\@%$(CHRONYVARDIR)%g;"
+
+man: $(MAN_FILES) $(MAN_IN_FILES)
+html: $(HTML_FILES)
+txt: $(TXT_FILES)
+docs: man html
+
+%.html: %.adoc
+	$(ADOC) $(ADOC_FLAGS) -b html -o - $< | $(SED) -e $(SED_COMMANDS) > $@
+
+%.man.in: %.adoc
+	$(ADOC) $(ADOC_FLAGS) -b manpage -o $@ $<
+
+%.man: %.man.in
+	$(SED) -e $(SED_COMMANDS) < $< > $@
+
+%.txt: %.html
+	$(HTML_TO_TXT) < $< > $@
+
+install: $(MAN_FILES)
+	[ -d $(DESTDIR)$(MANDIR)/man1 ] || mkdir -p $(DESTDIR)$(MANDIR)/man1
+	[ -d $(DESTDIR)$(MANDIR)/man5 ] || mkdir -p $(DESTDIR)$(MANDIR)/man5
+	[ -d $(DESTDIR)$(MANDIR)/man8 ] || mkdir -p $(DESTDIR)$(MANDIR)/man8
+	cp chronyc.man $(DESTDIR)$(MANDIR)/man1/chronyc.1
+	chmod 644 $(DESTDIR)$(MANDIR)/man1/chronyc.1
+	cp chronyd.man $(DESTDIR)$(MANDIR)/man8/chronyd.8
+	chmod 644 $(DESTDIR)$(MANDIR)/man8/chronyd.8
+	cp chrony.conf.man $(DESTDIR)$(MANDIR)/man5/chrony.conf.5
+	chmod 644 $(DESTDIR)$(MANDIR)/man5/chrony.conf.5
+
+install-docs: $(HTML_FILES)
+	[ -d $(DESTDIR)$(DOCDIR) ] || mkdir -p $(DESTDIR)$(DOCDIR)
+	for f in $(HTML_FILES); do \
+	  cp $$f $(DESTDIR)$(DOCDIR); \
+	  chmod 644 $(DESTDIR)$(DOCDIR)/$$f; \
+	done
+
+clean: distclean
+	rm -f $(MAN_IN_FILES)
+
+distclean:
+	rm -f $(MAN_FILES) $(TXT_FILES) $(HTML_FILES)