cmd: Fix a usage message: the % must be doubled for FOR variables.

[Francois Gouget]

The usage message was in fact documenting an old Wine bug.
---

I'm reluctant to change messages at this stage as it's going to cause 
fuzzying of the translations, but given that this message is plain wrong 
I think it's warranted. To verify this, try out the following commands:

$ echo 'for %%i in (1 2) do echo %%i' >foo.cmd; wine cmd /c 
foo.cmd

C:\>for %i in (1 2) do echo %i 
1
2
$ echo 'for %%i in (1 2) do echo %i' >foo.cmd; wine cmd /c foo.cmd

C:\>for %i in (1 2) do echo i 
i
i
$ echo 'for %i in (1 2) do echo %i' >foo.cmd; wine cmd /c foo.cmd

C:\>for i 
Syntax error
$ wine cmd
Wine CMD version 5.1.2600 (1.6-rc4)

C:\>for %i in (1 2) do echo %i
1
2


 programs/cmd/cmd.rc |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/programs/cmd/cmd.rc b/programs/cmd/cmd.rc
index 6f0d0d3..4b53ea9 100644
--- a/programs/cmd/cmd.rc
+++ b/programs/cmd/cmd.rc
@@ -65,8 +65,7 @@ preceding it with an @ sign.\n"
 \n\
 Usage: FOR %variable IN (set) DO command\n\
 \n\
-The requirement to double the % sign when using FOR in a batch file does\n\
-not exist in wine's cmd.\n"
+The % sign must be doubled when using FOR in a batch file.\n"
 
   WCMD_GOTO,
 "The GOTO command transfers execution to another statement within a\n\
-- 
1.7.10.4