[gtk+] build/Makefile.msvcproj: Improve documentation

[Chun-wei Fan <fanchunwei src gnome org>]

commit e382d9d9b57fcbef518385a73cda29d3a8743d77
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Mon Jan 9 12:11:33 2017 +0800

    build/Makefile.msvcproj: Improve documentation
    
    Tell people about what happens when generating projects when Visual
    Studio 2013 or later is required, and mention that the .headers are
    only needed when headers need to be copied.

 build/Makefile.msvcproj |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/build/Makefile.msvcproj b/build/Makefile.msvcproj
index a7bae54..a4e93a5 100644
--- a/build/Makefile.msvcproj
+++ b/build/Makefile.msvcproj
@@ -17,14 +17,19 @@
 #   MSVCPROJS = YourProject (can be multiple projects in a single srcdir)
 #   YourProject_FILES = $(libyourlib_1_0_SOURCES)
 #   YourProject_EXCLUDES = ... # list of sources to exclude, separated by '|', wildcards allowed; use random 
unsed value if none
+#   (the following 3 lines if headers need to be installed)
 #   YourProject_HEADERS_DIR = $(libyourlibincludedir)
 #   YourProject_HEADERS_INST = $(libyourlib_1_0_HEADERS)
 #   YourProject_HEADERS_EXCLUDES = ... # <list of headers to exclude from installation, separated by '|', 
wildcards allowed; use random unsed value if none>
 #
 #   dist-hook: \ # (or add to it if it is already there, note the vs9 items will also call the vs10 items in 
the process)
 #      $(top_builddir)/build/win32/vs9/YourProject.vcproj      \
-#      $(top_builddir)/build/win32/vs9/YourProject.headers
-
+#      $(top_builddir)/build/win32/vs9/YourProject.headers     # if headers need to be installed
+#
+#   --or, if Visual Studio 2013 or later is required--
+#   dist-hook: \ # (or add to it if it is already there, this does -not- call other vs items in the process)
+#      $(top_builddir)/build/win32/vs12/YourProject.vcxproj    \
+#      $(top_builddir)/build/win32/vs12/YourProject.vs12.headers       # if headers need to be installed
 
 # Private functions