Enhance grub2 install failure message.

The new message informs the useir will happen (they will boot into the old RHEL's kernel) so they
understand why they need to run the remediation.

jira: https://issues.redhat.com/browse/RHEL-29683

Author: abadger

repos/system_upgrade/common/actors/checkgrubcore/actor.py

@@ -46,11 +46,15 @@ def process(self):
                     reporting.Title('Leapp could not identify where GRUB2 core is located'),
                     reporting.Summary(
                         'We assumed GRUB2 core is located on the same device(s) as /boot, '
-                        'however Leapp could not detect GRUB2 on the device(s). '
-                        'GRUB2 core needs to be updated maually on legacy (BIOS) systems. '
+                        'however Leapp could not detect GRUB2 on those device(s). '
+                        'This means GRUB2 core will not be updated during the upgrade process and '
+                        'the system will probably ' 'boot into the old kernel after the upgrade. '
+                        'GRUB2 core needs to be updated manually on legacy (BIOS) systems to '
+                        'fix this.'
                     ),
                     reporting.Severity(reporting.Severity.HIGH),
                     reporting.Groups([reporting.Groups.BOOT]),
                     reporting.Remediation(
-                        hint='Please run "grub2-install <GRUB_DEVICE> command manually after the upgrade'),
+                        hint='Please run the "grub2-install <GRUB_DEVICE>" command manually '
+                        'after the upgrade'),
                 ])