Fix syntax error in a 'test_reboot_ras.robot' file

In a multiline string all lines after the first one
should start with a '...' prefix.

Change-Id: I912de2aff601b1957c4bb3175fc7f516e401ad32
Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
diff --git a/openpower/ras/test_reboot_ras.robot b/openpower/ras/test_reboot_ras.robot
index e97733a..b4e6c1c 100755
--- a/openpower/ras/test_reboot_ras.robot
+++ b/openpower/ras/test_reboot_ras.robot
@@ -1,6 +1,6 @@
 *** Settings ***
 Documentation       This suite tests error log callout handling when checkstop
-                    is injected through HOST/BMC and BMC rebooted.
+...                 is injected through HOST/BMC and BMC rebooted.
 
 Resource            ../../lib/openbmc_ffdc.robot
 Resource            ../../lib/openbmc_ffdc_utils.robot