Fix and clean top .gitignore

Removed vmlinux* rule because it matches too many useful files, replacing
it with rules matching filetype by filename (e.g. *.gz). Also unignored
.mailmap from the top directory. Added a comment telling the user how to
check for tracked files being ignored.
Signed-off-by: NEduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

.gitignore

@@ -3,6 +3,10 @@
 # subdirectories here. Add them in the ".gitignore" file
 # in that subdirectory instead.
 #
+# NOTE! Please use 'git-ls-files -i --exclude-standard'
+# command after changing this file, to see if there are
+# any tracked files which get ignored after the change.
+#
 # Normal rules
 #
 .*
@@ -18,19 +22,21 @@
 *.lst
 *.symtypes
 *.order
+*.elf
+*.bin
+*.gz
 
 #
 # Top-level generic files
 #
 tags
 TAGS
-vmlinux*
-!vmlinux.lds.S
-!vmlinux.lds.h
+vmlinux
 System.map
 Module.markers
 Module.symvers
 !.gitignore
+!.mailmap
 
 #
 # Generated include files