Fix issue #219: install documentation fully and properly.

- Install the top-level README.md, which wasn't installed before.
- Install docs to /usr/local/share/doc rather than /usr/local/share.

Makefile

@@ -3,6 +3,7 @@ NAME=zsh-syntax-highlighting
 INSTALL?=install -c
 PREFIX?=/usr/local
 SHARE_DIR?=$(DESTDIR)$(PREFIX)/share/$(NAME)
+DOC_DIR?=$(DESTDIR)$(PREFIX)/share/doc/$(NAME)
 ZSH?=zsh # zsh binary to run tests with
 
 # Have the default target do nothing.
@@ -11,12 +12,23 @@ all:
 
 install:
 	$(INSTALL) -d $(SHARE_DIR)
-	cp -r .version zsh-syntax-highlighting.zsh highlighters $(SHARE_DIR)
+	$(INSTALL) -d $(DOC_DIR)
+	$(INSTALL) .version zsh-syntax-highlighting.zsh $(SHARE_DIR)
+	$(INSTALL) COPYING.md README.md changelog.md $(DOC_DIR)
 	if [ x"true" = x"`git rev-parse --is-inside-work-tree 2>/dev/null`" ]; then \
 		git rev-parse HEAD; \
 	else \
 		cat .revision-hash; \
 	fi > $(SHARE_DIR)/.revision-hash
+	:
+# The [ -e ] check below is to because sh evaluates this with (the moral
+# equivalent of) NONOMATCH in effect, and highlighters/*.zsh has no matches.
+	for dirname in highlighters highlighters/*/ ; do \
+		$(INSTALL) -d "$(SHARE_DIR)/$$dirname"; \
+		$(INSTALL) -d "$(DOC_DIR)/$$dirname"; \
+		for fname in "$$dirname"/*.zsh ; do [ -e "$$fname" ] && $(INSTALL) "$$fname" "$(SHARE_DIR)/$$dirname"; done; \
+		for fname in "$$dirname"/*.md ; do  [ -e "$$fname" ] && $(INSTALL) "$$fname" "$(DOC_DIR)/$$dirname"; done; \
+	done
 
 test:
 	@result=0; \