Documentation: add top level 'make help' output for Sphinx

While there's slight overlap with the DocBook help now, this can stay
intact when the DocBook help goes away.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index e0c7e1e..496d429 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -218,7 +218,7 @@
 ###
 # Help targets as used by the top-level makefile
 dochelp:
-	@echo  ' Linux kernel internal documentation in different formats:'
+	@echo  ' Linux kernel internal documentation in different formats (DocBook):'
 	@echo  '  htmldocs        - HTML'
 	@echo  '  pdfdocs         - PDF'
 	@echo  '  psdocs          - Postscript'
@@ -227,7 +227,7 @@
 	@echo  '  installmandocs  - install man pages generated by mandocs'
 	@echo  '  cleandocs       - clean all generated DocBook files'
 	@echo
-	@echo  'make DOCBOOKS="s1.xml s2.xml" [target] Generate only docs s1.xml s2.xml'
+	@echo  '  make DOCBOOKS="s1.xml s2.xml" [target] Generate only docs s1.xml s2.xml'
 	@echo  '  valid values for DOCBOOKS are: $(DOCBOOKS)'