am --abort: Add to bash-completion and mention in git-rerere documentation

The git-rerere documentation talks about commands that invoke
"git rerere clear" automatically. git am --abort is added and
a typo is fixed additionally.
Signed-off-by: NStephan Beyer <s-beyer@gmx.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-rerere.txt

@@ -37,7 +37,7 @@ its working state.
 'clear'::
 
 This resets the metadata used by rerere if a merge resolution is to be
-is aborted.  Calling 'git-am --skip' or 'git-rebase [--skip|--abort]'
+aborted.  Calling 'git-am [--skip|--abort]' or 'git-rebase [--skip|--abort]'
 will automatically invoke this command.
 
 'diff'::

contrib/completion/git-completion.bash

@@ -489,7 +489,7 @@ _git_am ()
 {
 	local cur="${COMP_WORDS[COMP_CWORD]}" dir="$(__gitdir)"
 	if [ -d "$dir"/rebase-apply ]; then
-		__gitcomp "--skip --resolved"
+		__gitcomp "--skip --resolved --abort"
 		return
 	fi
 	case "$cur" in