[libpng16] Revised INSTALL document.

INSTALL

@@ -30,9 +30,15 @@ On Unix/Linux and similar systems, you can simply type
 
 and ignore the rest of this document.  "/path" is the path to the directory
 where you want to install the libpng "lib", "include", and "bin"
-subdirectories.  Note that "configure" is only included in the "*.tar"
-distributions and not in the "*.zip" or "*.7z" distributions. If you
-downloaded one of those distributions, see "Building with makefiles",
+subdirectories.
+
+If you downloaded a GIT clone, you will need to run ./autogen.sh before
+running ./configure, to create "configure" and "Makefile.in" which are
+not included in the GIT repository.
+
+Note that "configure" is only included in the "*.tar" distributions and not
+in the "*.zip" or "*.7z" distributions. If you downloaded one of those
+distributions, see "Building with project files" or "Building with makefiles",
 below.
 
 II. Rebuilding the configure scripts
@@ -114,8 +120,7 @@ Your directory structure should look like this:
       libpng  (this directory)
           INSTALL (this file)
           README
-          *.h
-          *.c
+          *.h, *.c  => libpng source files
           CMakeLists.txt    =>  "cmake" script
           configuration files:
              configure.ac, configure, Makefile.am, Makefile.in,
@@ -126,7 +131,7 @@ Your directory structure should look like this:
              arm-neon, conftest, examples, gregbook, libtests, pngminim,
              pngminus, pngsuite, tools, visupng
           projects
-             cbuilder5, visualc71, owatcom, vstudio, xcode
+             cbuilder5, owatcom, visualc71, vstudio, xcode
           scripts
              makefile.*
              *.def (module definition files)
@@ -134,11 +139,7 @@ Your directory structure should look like this:
           pngtest.png
           etc.
       zlib
-          README
-          *.h
-          *.c
-          contrib
-          etc.
+          README, *.h, *.c contrib, etc.
 
 If the line endings in the files look funny, you may wish to get the other
 distribution of libpng.  It is available in both tar.gz (UNIX style line
@@ -147,7 +148,7 @@ endings) and zip (DOS style line endings) formats.
 VI. Building with project files
 
 If you are building libpng with MSVC, you can enter the
-libpng projects\visualc6 or vstudio directory and follow the instructions
+libpng projects\visualc71 or vstudio directory and follow the instructions
 in README.txt.
 
 Otherwise enter the zlib directory and follow the instructions in zlib/README,