correct output from "make helpall"

* Makefile: correct definitions to have "make helpall" display the
  output in the way it was intended.  Remove documentation for
  "cleanrel" as it is not intended to be used except on the release
  server; this target may move into server.mk, but for now leave it
  in targets.mk.

Makefile

@@ -12,8 +12,7 @@ all::
 # Describe valid make targets for org-mode.
 .PHONY:	targets help helpall
 targets:	help
-helpall::	help
-help::
+help helpall::
 	$(info )
 	$(info Getting Help)
 	$(info ============)
@@ -57,24 +56,23 @@ helpall::
 	$(info make cleandocs     - ditto)
 	$(info make cleanlisp     - remove built Org ELisp files)
 	$(info make cleanelc      - ditto)
-	$(info make cleanrel      - remove release remnants)
 	$(info make cleantest     - remove check remnants)
 	$(info make clean-install - remove previous Org installation)
 	$(info )
 	$(info Documentation)
 	$(info =============)
-help::
+help helpall::
 	$(info make doc           - build all documentation)
 helpall::
 	$(info make docs          - ditto)
-help::
+help helpall::
 	$(info make info          - build Info documentation)
 helpall::
 	$(info make html          - build HTML documentation)
 	$(info make pdf           - build PDF documentation)
 	$(info make card          - build reference cards)
 	$(info make refcard       - ditto)
-help::
+help helpall::
 	$(info )
 	$(info Installation)
 	$(info ============)
@@ -83,7 +81,7 @@ helpall::
 	$(info make install-etc   - build and install files in /etc)
 	$(info make install-lisp  - build and install Org Elisp files)
 	$(info make install-info  - build and install Info documentation)
-help::
+help helpall::
 	@echo ""
 
  include targets.mk	# toplevel make machinery