Manual pages (#1346)

* Add manual pages

Generate manual pages from the README and extend README with Name and
Description sections.

The generation requires 'ronn' which may not be available. Just check in
all generated manual pages.

Makefile.doc

@@ -0,0 +1,30 @@
+ORG:=organization=CoreDNS
+RONN:=ronn -r
+PLUGINS:=$(wildcard plugin/*/README.md)
+READMES:=$(subst plugin/,,$(PLUGINS))
+READMES:=$(subst /README.md,,$(READMES))
+PLUGINS:=$(subst plugin/,corendns-,$(PLUGINS))
+PLUGINS:=$(subst /README.md,(7),$(PLUGINS))
+
+all: man/coredns.1 plugins
+
+man/coredns.1: coredns.1.md
+	sed -e 's/^\(#.*\)/\U\1/' $< > $@.md
+	sed -i -e "s/@@PLUGINS@@/$(PLUGINS)/" $@.md
+	$(RONN) --$(ORG) --manual='CoreDNS' $@.md
+	rm $@.md
+
+.PHONY: plugins
+plugins:
+	for README in $(READMES); do \
+	    $(MAKE) -f Makefile.doc man/coredns-$$README.7; \
+	done
+
+man/coredns-%.7: plugin/%/README.md
+	sed -e 's/^\(#.*\)/\U\1/' $< > $@.md
+	$(RONN) --$(ORG) --manual='CoreDNS plugins' $@.md
+	rm $@.md
+
+PHONY: clean
+clean:
+	rm -f man/*