Added some comments and spaces in Git's ignore file

It helps to understand why a file is present in this file, which
in turn can help to understand where a file comes from and it makes
updates to the file easier

.gitignore

@@ -1,5 +1,4 @@
-*.lo
-*.o
+# These files are generated by the AutoTools
 *Makefile
 *Makefile.in
 .deps/
@@ -11,7 +10,6 @@ config-paths.h
 config.guess
 config.h
 config.h.in
-config.h.in~
 config.log
 config.status
 config.sub
@@ -23,11 +21,18 @@ ltmain.sh
 missing
 mkinstalldirs
 stamp-h1
-contrib/WindowMaker.spec
 m4/
+
 src/wconfig.h
+
+# These files are compilation stuff
+*.lo
+*.o
+
+# These are compilation results
 src/wmaker
 test/wtest
+
 util/convertfonts
 util/geticonset
 util/getstyle
@@ -43,13 +48,14 @@ util/wmsetbg
 util/wmsetup
 util/wxcopy
 util/wxpaste
+
 wrlib/get-wraster-flags
 wrlib/libwraster.la
 wrlib/tests/testdraw
 wrlib/tests/testgrad
 wrlib/tests/testrot
 wrlib/tests/view
-wrlib/wrlib.pc
+
 WINGs/Examples/colorpick
 WINGs/Examples/connect
 WINGs/Examples/fontl
@@ -62,17 +68,26 @@ WINGs/Tests/testmywidget
 WINGs/Tests/wmfile
 WINGs/Tests/wmquery
 WINGs/Tests/wtest
-WINGs/WINGs.pc
 WINGs/get-wings-flags
 WINGs/get-wutil-flags
 WINGs/libWINGs.a
 WINGs/libWINGs.la
 WINGs/libWUtil.a
 WINGs/libWUtil.la
+
 WPrefs.app/WPrefs
+
+# These files are generated from make rules
+wrlib/wrlib.pc
+WINGs/WINGs.pc
+
+contrib/WindowMaker.spec
 WindowMaker/Defaults/WMRootMenu
 WindowMaker/Defaults/WMState
 WindowMaker/Defaults/WMWindowAttributes
 WindowMaker/Defaults/WindowMaker
 WindowMaker/IconSets/Default.iconset
 wmlib/libWMaker.la
+
+# Some text editors generate backup files
+config.h.in~