Remove unnecessary instructions in `kdump` setup
Remove unnecessary instructions in `kdump` setup

Remove example on changing the local crash dump location.
The precise location on the filesystem likely does not matter, so
we should remove this example of an uncommon use case.
We have observed that users skimming through the docs may have
mistaken this example for a required step, and unnecessarily
configuring their crash dump location to `/var/usrlocal/cores`.

Remove unnecessary bootimage location configuration.
Fix in `kexec-tools` is in RHEL 8.4 and also backported to 8.3.
xref: https://bugzilla.redhat.com/show_bug.cgi?id=1866611

Remove instruction to use `kexec_load()` over `kexec_file_load()`.
The default `kexec_file_load()` appears to be working fine in
RHCOS.

Add note about `kdump` on LUKS.
Currently, `kdump` does not support saving the crash dump on the
local filesystem if it is encrypted by LUKS. Add a note that
manual configuration to use a remote dump is required if using LUKS.

Fix some wording for more clarity.

vikram-redhat/openshift-docs,vikram-redhat/openshift-docs,vikram-redhat/openshift-docs,vikram-redhat/openshift-docs,vikram-redhat/openshift-docs