documentation/Makefile: new 'edison' variable for YP dev manual.

I discovered that the figures used in this manual differ depending
on the branch.  There are two figures that are different.  Thus,
the TARFILES variable in the makefile needed to be conditionalized.
If it is not, then the process that makes the tarball throws errors
because it cannot find the two figures from the other branch.

To fix this I introduced the 'BRANCH' variable.  It is to be used
only when you make or publish the YP Development Manual.  And, you
only use it to specify 'edison'.  If you are building from the 'master'
branch you don't need to use it.

Comments in the file have been updated to explain usage.

(From yocto-docs rev: a404eadbeeb6eb7476d8739bd07ecd071e9ff7da)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/Makefile

@@ -1,48 +1,61 @@
 # This is a single Makefile to handle all generated Yocto Project documents.
 # The Makefile needs to live in the documents directory and all figures used
-# in any manuals must be PNG files and live in the individual book's figures
-# directory.
+# in any manuals must be .PNG files and live in the individual book's figures
+# directory.  Note that the figures for the Yocto Project Development Manual
+# differ between the 'master' and 'edison' branches.
 #
 # The Makefile has these targets:
 #
-#    pdf: generates a PDF version of a manual.  Not valid for the Quick Start
-#    html: generates an HTML version of a manual.
-#    tarball: creates a tarball for the doc files.
+#    pdf:      generates a PDF version of a manual.  Not valid for the Quick Start
+#    html:     generates an HTML version of a manual.
+#    tarball:  creates a tarball for the doc files.
 #    validate: validates 
-#    publish: pushes generated files to the Yocto Project website
-#    clean: removes files
+#    publish:  pushes generated files to the Yocto Project website
+#    clean:    removes files
 #
 # The Makefile generates an HTML and PDF version of every document except the
 # Yocto Project Quick Start.  The Quick Start is in HTML form only.  The variable
-# The command-line argument DOC represents the folder name in which a particular 
-# document is stored.  The command-line argument VER represents the distro 
-# version of the Yocto Release for which the manuals are being generated.
+# DOC is used to indicate the folder name for a given manual. The variable
+# VER represents the distro version of the Yocto Release for which the manuals 
+# are being generated.  The variable BRANCH is used to indicate the 'edison'
+# branch and is used only when DOC=dev-manual (making the YP Development
+# Manual).  
+#
 # To build the HTML and PDF versions of the manual you must invoke the Makefile
 # with the DOC argument.  If you are going to publish the manual then you 
 # you must invoke the Makefile with both the DOC and the VER argument.
+# If you are building the 'edison' version of the YP DEvelopment Manual then
+# you must use the DOC and BRANCH arguments.  
 #
 # Examples:
 #
 #     make DOC=bsp-guide
 #     make DOC=yocto-project-qs
 #     make pdf DOC=poky-ref-manual
+#     make DOC=dev-manual BRANCH=edison
 #
 # The first example generates the HTML and PDF versions of the BSP Guide.
 # The second example generates the HTML version only of the Quick Start.  Note that 
 # the Quick Start only has an HTML version available.  The third example generates 
-# both the PDF and HTML versions of the Yocto Project Reference Manual.
+# both the PDF and HTML versions of the Yocto Project Reference Manual. The 
+# last example generates both the PDF and HTML 'edison' versions of the YP 
+# Development Manual.
 #
 # Use the publish target to push the generated manuals to the Yocto Project 
 # website.  All files needed for the manual's HTML form are pushed as well as the 
 # PDF version (if applicable).  
 # Examples:
 #
-#    make publish DOC=bsp-guide VER=1.1
-#    make publish DOC=adt-manual VER=1.1
+#    make publish DOC=bsp-guide VER=1.2
+#    make publish DOC=adt-manual VER=1.2
+#    make publish DOC=dev-manual VER=1.1.1 BRANCH=edison
+#    make publish DOC=dev-manual VER=1.2 
 #
-# The first example publishes the 1.1 version of both the PDF and HTML versions of 
-# the BSP Guide.  The second example publishes the 1.1 version of both the PDF and 
-# HTML versions of the ADT Manual.
+# The first example publishes the 1.2 version of both the PDF and HTML versions of 
+# the BSP Guide.  The second example publishes the 1.2 version of both the PDF and 
+# HTML versions of the ADT Manual. The third example publishes the PDF and HTML
+# 'edison' versions of the YP Development Manual.  Finally, the last example publishes
+# the PDF and HTML 'master' versions of the YP Development Manual. 
 #
 
 ifeq ($(DOC),bsp-guide)
@@ -71,14 +84,27 @@ ALLPREQ = html pdf tarball
 # message for .PNG files that are not present when building a particular branch.  The 
 # list of files is all-inclusive for all branches.
 #
+
+	ifeq ($(BRANCH),edison)
 TARFILES = style.css dev-manual.html dev-manual.pdf \
            figures/app-dev-flow.png figures/bsp-dev-flow.png figures/dev-title.png \
            figures/git-workflow.png figures/index-downloads.png figures/kernel-dev-flow.png \
-           figures/kernel-example-repos.png figures/kernel-example-repos-edison.png \
+           figures/kernel-example-repos-edison.png \
            figures/kernel-overview-1.png figures/kernel-overview-2.png \
-           figures/kernel-overview-3.png figures/kernel-overview-3-edison.png \
+           figures/kernel-overview-3-edison.png \
            figures/source-repos.png figures/yp-download.png \
            figures/wip.png
+	else
+TARFILES = style.css dev-manual.html dev-manual.pdf \
+           figures/app-dev-flow.png figures/bsp-dev-flow.png figures/dev-title.png \
+           figures/git-workflow.png figures/index-downloads.png figures/kernel-dev-flow.png \
+           figures/kernel-example-repos.png \
+           figures/kernel-overview-1.png figures/kernel-overview-2.png \
+           figures/kernel-overview-3.png \
+           figures/source-repos.png figures/yp-download.png \
+           figures/wip.png
+	endif
+
 MANUALS = $(DOC)/$(DOC).html $(DOC)/$(DOC).pdf
 FIGURES = figures
 STYLESHEET = $(DOC)/*.css