ShellPkg/setvar: Correct typo in setvar help message

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
diff --git a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.uni b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.uni
index bd1726b..06865a4 100644
--- a/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.uni
+++ b/ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.uni
@@ -813,9 +813,9 @@
 "  3. If = is not specified, then the current variable contents are displayed.\r\n"

 "  4. If =data is specified, then the variable's value is changed to the value\r\n"

 "     specified by data.\r\n"

-"  5. -bs, -rt and -nv are only useful if the variable already exists.\r\n"

-"  6. If the variable already exists and the attributes cannot be changed,\r\n"

-"     then -1 is returned. \r\n"

+"  5. -bs, -rt and -nv are only useful if the variable does not exist.\r\n"

+"  6. If the variable already exists, the attributes cannot be changed, and the"

+"     flags will be ignored.\r\n"

 ".SH RETURNVALUES\r\n"

 " \r\n"

 "RETURN VALUES:\r\n"