docs: fix chroot path for centos8
% ohpc_comment_header Create chroot based compute image \ref{sec:assemble_bos}
\begin{lstlisting}[language=bash,literate={-}{-}1,keywords={},upquote=true,keepspaces,literate={BOSSHORT}{\baseosshort{}}1]
# Save chroot location for compute image
-[sms](*\#*) export CHROOT=/install/netboot/BOSVER/x86_64/compute/rootimg/
+[sms](*\#*) export CHROOT=/install/netboot/BOSSHORT/x86_64/compute/rootimg/
# Build initial chroot image
[sms](*\#*) genimage BOSSHORT-x86_64-netboot-compute
\end{lstlisting}
