$ mkdir /tmp/test_git
$ cd /tmp/test_git
$ git init
Initialized empty Git repository in /home/chris/tmp/thing/.git/

$ echo '(kill-emacs)' > killer.el

$ git add killer.el

$ git ci -m "Killer"
[master (root-commit) dce2981] Killer
 1 file changed, 1 insertion(+)
 create mode 100644 killer.el

$ mkdir -p nested/sub/directory

$ touch nested/sub/directory/some_file.el

$ git st

# On branch master
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#       nested/
nothing added to commit but untracked files present (use "git add" to track)

$ mkdir nested/dir/ -p

$ touch nested/dir/script.el

$ git st

# On branch master
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#       nested/
nothing added to commit but untracked files present (use "git add" to track)

##
## SHELL GLOBBING DOES NOT ADD FILES IN DIRECTORIES
##

$ git add *.el
$ git st
# On branch master
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#       nested/
nothing added to commit but untracked files present (use "git add" to track)

##
## NOW, WITH SINGLE QUOTES AFTER --
##

$ git add -- '*.el'
$ git st

# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#       new file:   nested/dir/script.el
#       new file:   nested/sub/directory/some_file.el
#