i18n: add--interactive: mark simple here-documents for translation

Mark messages in here-documents without interpolation for translation.

The here-document delimiter \EOF, which is the same as 'EOF', indicates
that the text is to be treated literally without interpolation of its
content.  Unfortunately xgettext is not able to extract here-documents
delimited with \EOF but it is with delimiter enclosed in single quotes.
So change \EOF to 'EOF', although in this case does not make
difference what variation of here-document to use since there is nothing
to interpolate.

Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-add--interactive.perl

@@ -638,7 +638,7 @@ sub list_and_choose {
 }
 
 sub singleton_prompt_help_cmd {
-	print colored $help_color, <<\EOF ;
+	print colored $help_color, __ <<'EOF' ;
 Prompt help:
 1          - select a numbered item
 foo        - select item based on unique prefix
@@ -647,7 +647,7 @@ EOF
 }
 
 sub prompt_help_cmd {
-	print colored $help_color, <<\EOF ;
+	print colored $help_color, __ <<'EOF' ;
 Prompt help:
 1          - select a single item
 3-5        - select a range of items
@@ -1581,7 +1581,9 @@ sub quit_cmd {
 }
 
 sub help_cmd {
-	print colored $help_color, <<\EOF ;
+# TRANSLATORS: please do not translate the command names
+# 'status', 'update', 'revert', etc.
+	print colored $help_color, __ <<'EOF' ;
 status        - show paths with changes
 update        - add working tree state to the staged set of changes
 revert        - revert staged set of changes back to the HEAD version